| Using geostatistical method to analyze the spatial structure of soil heavy metal can reflect random, structure, independence and relativity of all kinds of soil heavy metal, and reflect its changeable characteristics further in details. Grey correlated analysis, which was based on the relation analysis between soil heavy metal forms and soil physical and chemical characteristics, can open out the main inner factors which drive soil heavy metal changing (physical and chemical characteristics).The description statistic of the content of different forms (exchangeable, bound to carbonate, bound to Iron and Manganese, bound to organic matter, residue) of heavy metals showed, except Cd in soil was priority to bound to Iron and Manganese oxides, and the average content was 0.086mg/kg, which accounted for 32.21%, the rest four elements, Cu , Pb, Cr, Zn gives priority to residue form, and the average content was 26.96mg/kg, 39.63 mg/kg, 98.63 mg/kg and 67.84 mg/kg, accounting for 75.92%, 59.11%, 92.63%, 72.16% of total content. The orders of different forms of five elements were, bound to Iron and Manganese oxides > residue form > bound to carbonate > bound to organic matter form > exchangeable form for Cd, residue form > bound to organic matter > bound to Iron and Manganese > bound to carbonate > exchangeable form for Cu, residue form > bound to organic matter > bound to iron and manganese > bound to carbonate > exchangeable form for Pb, residue form > bound to organic matter > bound to iron and manganese > bound to carbonate > exchangeable form for Cr, residue form > bound to organic matter > bound to iron and manganese > bound to carbonate > exchangeable form for Zn. At the same time, the proportion of activity form in total content of five elements was quite different. The content of active Cd was 0.194 mg/kg accounting for 72.66%, which was the highest proportion in total content. The content of active Pb was 27.41mg/kg, accounting for 40.89% which was the second proportion in total content. The content of active Zn and Cu were 26.17mg/kg and 8.55mg/kg accounting for 27.84% 24.08%, which was the third proportion in total content. The content of active Cr was 7.83mg/kg accounting for 7.37%, which was the last proportion in total content. The result indicated that Cd had the highest activity and Cr had the lowest activity. In addition, the changes of coefficients of variation among five forms for Cd and Cu were relatively large. All kinds of soil Cd changed distinctly, and the range of coefficient of variation was 43%~123%, which of bound to carbonate was the biggest 122.64%. The coefficient of variation of every form of heavy metal Cu was big; the biggest was bound to Iron and Manganese (103.23%). And it belonged tointension variation; the others belonged to middle variation. The range of coefficient of variation of different forms for the rest three elements was 25%~75%, which accorded with moderate variance.The analysis of spatial structure variability and inner factors (soil physic and chemic properties) showed that, bound to organic matter Cd had spatial autocorrelation, its structural factors affecting Cd accounted for 81.2%, and there was bigger variation mainly at southeast-northwest (135° direction). The main influencing factors were coarse silt, pH and organic matters. The rest forms had middling relativity, mainly happened at southwest and northeast (45° direction). The results of analyzing the inner factors indicated that major factors influenced exchangeable Cd, bound to carbonate Cd, bound to Iron and Manganese oxides Cd and active Cd were pH, bulk density and medium fine silt. The variability of exchangeable Cu was intensity spatial autocorrelation, and the other was moderate. The direction of spatial variability of every form mainly represented 45° and 135°. The inner factor of impacting the content of exchangeable Cu was organic matters, and impacting the content of organic combining conditions Cu was clay, sand and organic matters. Soil clay and organic matters affected the content of active Cu in greater extent, but the relationship between bound to carbonate and bound to Iron and Manganese form did not. Bound to carbonate, bound to organic matter form and active Pb were intensity spatial relativity-self in short distance, exchangeable form and bound to Iron and Manganese form were moderate spatial relativity-self in longer distance. The variance mainly showed in the direction of northeast and southwest (135°), next in the direction of southeast and northwest (45°). Soil pH obviously influenced the distribution of exchangeable form and bound to carbonate content, and soil organic matter also influenced the distribution of bound to carbonate content. The main factors, which influenced the content of bound to Iron and Manganese form were soil organic matter and pH. The main factor, which influenced the content of active Pb was soil organic matter. The main factors, which influenced the content of bound to organic matter Pb were soil organic matter, clay, CEC and sand. All forms of Cr had intensity spatial relativity-self except for exchangeable form and active form, which had moderate spatial relativity-self. The relativity analysis between soil physical, chemical characteristics and content of different forms of Cr showed that, soil clay had notable positive relativity with bound to carbonate, bound to Iron and Manganese and bound to organic matter form. Bound to organic matter form and active form also had notable positive relativity with soil organic matter; CEC was the main factor, which influenced the content of active Cr. All forms of Zn had intensity spatial relativity-self except for exchangeable form, which had moderate spatial relativity-self. pH mainly influenced exchangeable form, bound to carbonate and bound to Iron and Manganese. Organic matter was the main factor, which influence the content of various form of Zn except exchangeable Zn. There were many factors, which influenced the content of bound to Iron and Manganese, such as clay, medium fine silt, sand and CEC, except for pH and organic matter. The main factors which influenced the active Zn were clay, sand, organic matter and CEC.The spatial interpolation analysis of different forms for five elements showed that, the higher area of Cd content mainly distributed in the north, northeast Deyang and Pengzhou district, and the lower area mainly distributed in Wenjiang, Chongzhou, and Qionglai et al, except for bound to organic matter Cd. The highest value region of exchangeable form, bound to carbonate and bound to Iron and Manganese content mainly existed in the north of Chongzhou, Pengzhou, which was distributed in the northwest of study area, and in the southeast of Shuangliu, suburb of Chengdu and Xindu, and in some parts of Deyang. The distribution trend of bound to organic matter form and active Cu content was the same with the three forms in front except was lower in northeast Deyang. The distribution of exchangeable form and bound to carbonate content appeared as strip belts or gobbets, the highest value belts mainly existed in northwest Dujiangyan and northeast Deyang. The distribution of bound to Iron and Manganese, bound to organic matter form and active form content appeared as strip belt, the highest value belts of bound to Iron and Manganese mainly existed in Chongzhou and Xinjin. The highest value belts of bound to organic matter form and active form content existed in north Pengzhou, northwest Dujiangyan and north Shuangliu and Xinjin. The distribution trends of content of various forms for Cr were different, but all had the characteristics that lower in the middle of the plain close to west, higher in the north region. The spatial variability of various forms of Zn mainly indicated in the direction of 45°, the highest value belt most existed in north Pengzhou, Chongzhou, and some parts of Deyang.
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