| The scientific researches and progresses of wetland and the applications and developments of the constructed wetland were summarized in this paper. The wetland resources of Xi'an region and mechanism and dynamics parameters of water pollution control in the constructed wetland were also studied through the investigation, the simulated test and theoretical analysis, Under the translated analysis of the reference to the satellite-remote sensing, The comprehensive analyses and systematically studying on the distribution, area, structural types and functional features of wetland resources in Xi'an periphery area, the volution of wetland environment, the ecological function of wetland and est were first systemically studied. On the base of the classify statistics, the research and application of the constructed wetland was first reviewed. The survey showed that the total area of weltland in Xi' an is 960.96km2, in which natural wetland is 822.05km2 and constructed wetland is 78.91km2. the economics value wetland Systems is 3 158.65 ×108 $, the estimation of ecologicalwater demand is 14.49 × 108 m3. For keeping the normal function of the ecological wetland systerm, the water demand must be supplied for 5.4 × 108m3.The investigation and determined results of the normal types of water-plants in wetland indicated that the major types of polluting-tolerant suited to the local climate are the seed plants (15 types), the aquatic plants (64 types), The treatment of sewage by the constructed wetland with local recommendation and water plants should be selected firstly.A pilot plant of constructed wetland with UASB as a primary treatment was built up to treat municipal wastewater, effluent from secondary treatment and environmental-hormone contained wastewater, respectively. The results showed that removal efficiencies of CODcr, BOD5, NH3-N and TP can reach 90.56%, 97.9%, 85.56% and 901% respectively with a 7.0 cm/d of HLR. On the basisof the experiment, a circular hybrid constructed wetland is put forward.HLR is linear with that of removing contaminates. the degrading law of COD is firstly fast then slow, and the degrading process of COD will be verified to follow quadratic dynamics equation as following CL = C0 exp(K1L + K2L2), the degrading number isK1 =-0.0157, K2 =4.326×10-5 in the rang or 3.5cm/d, 70cm/d, 10.5cm/d and 14.0 cm/d respectively, The rate of de-nitrogen is positive correlative with the hydraulic retention period and the TN number of removing is satisfied with preliminary kinetics, the degrading number (KT) is 0.9219 (R2=0.9952) Utilizing the model of the ecological plants, water-body and basic land we can establish the mathematical model of Phosphorous circle and make the resolution. The ability of removing TP mainly depend on the absorption of the plant and the precipitate of micro-organism from basic mud.As to the low concentration of environmental-hormone wastewater, to a degree the model of experimental wetland is also the ability to degrade, in which the average load of removing Pb and Hg is 6.95(mg/m2·d), and 0.95 (mg/m2·d) respectively. The degrading process of ArOH will be verified to follow quadratic dynamics equation as following.When the aeration is mixed to the corridor in the bed-body, the rate could be raised by 15 %. Within the scope of 15.0mg/l for the optimum in LAS concentration, the degrading process will be verified to follow quadratic dynamics equation as following dc/dt=a(?)+bc+d, in which a = 0.0782, b=3.6165 and d =-56.125.This paper also to the mechanism of sewage purification under the control of wetland ecological system, the model design to the technological application of the constructed wetland, the selected parameters and the influence factor were summed, analyzes and discusses. The parameters were used to direct the engineering design and the concrete instance wok all in a good state. which has the specific guidance meaning of restoration and control of Xi'an wetland environment.
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