| Artemisia ordosica krasch. and A. arenaria D.C. are both sub-shrubs of Artemisia in Asteraceaer, the main sand-fixing plants in arid desert and have played an important role in desert eco-environment protection and agriculture production. The paper has researched on impact of seed germinating ratio at different sand depth, growth and developing regulation, photosynthesis and evaporation characteristics, population distribution patterns, population niche, branching module characteristics and wind-break and sand-fixation effects. The main results are as follows.The average weight of 1 thousand seeds of A. ordosica krasch. and A. arenaria D.C is 0.311g and 0.547g respectively. The germinating and seedling ratio is both more than 60% when seed depth in the sand is 0～4mm, it is reduced quickly when seed depth is 6～8mm, especially, reduced remarkably in 4～20mm, the ratio is both reduced and different with the seed depth increasing in the sand, the seed can not germinate when the depth in the sand reaches to more than 20 mm.A. ordosica krasch. and A. arenaria D.C. have similar Phenological phase in research area, the yearly growth period is about 230d from the middle of March to early November. The nutrition branches can grow continually in life, however, fertile branches have only one growth season.The tendency of diurnal change on photosynthesis rate of A. ordosica krasch. and A. arenaria D.C. indicates single peak curves and also shows linear rising and declining tendency respectively. With the increasing of light quantum density, photosynthesis peak of A. ordosica krasch. occurs latter than that of A. arenaria D.C. in a day, A. ordosica krasch. is 11:00 am and peak value is 21.2272μmol·m-2·s-1,however, A. arenaria D.C. is 9:00 am and peak value is 20.8348μmol·m-2·s-1. The pure photosynthesis rate of two species reaches the peak values firstly, and then decline quickly. The value of photosynthesis rate of A. ordosica krasch .rising or reducing is later than that of A. arenaria D.C. with the light quantum increasing and reducing in a day, and the value of A. ordosica krasch is higher than that of A. arenaria D.C. generally. Diurnal change of evaporating rate of A. ordosica krasch. indicates double peak curves which occur at 9:00 and 13:00 in a day, the values are 21.258 mol·m-2·s-1 and 24.404 mol·m-2·s-1. However, Diurnal change of evaporating rate of A. arenaria D.C. indicates single peak curve, it occurs 13:00 in a day and peak value is 16.444 mol·m-2·s-1. The change range of evaporating rate of A. ordosica krasch. is 30.38% more than that of A. arenaria D.C.Population distribution patterns of the species are much similar under analysis methods by point distribution of population and space distribution index, the individual distribution patterns on horizontal space are hierachical clump.The breadth values on ecological-niche of A. ordosica krasch. are 0.051, 0.194, 0.224 from shifting sandy land, semi-fixed sandy land to fixed sandy land respectively, and the values of A. arenaria D.C. are 0.499, 0.206, 0.035, individually. And breadth value on ecological-niche in different succession stage has bigger difference, the difference of eco-niche overlaps between two species and other species is obvious, eco-niche overlap value of A. ordosica krasch. with other species at fixed sandy land is big, however, A. arenaria D.C. is big at shifting sandy land. And their eco-niche overlap is developing and changing with vegetation succession stages.The first, second and third grade branches of the two species belong to the medium branching angle patterns (the branch angle is 50o～60o, and the plant top is 35o～50o generally). Branch growth can use resources fully in space and time through adaptability of long history succession.On branching module of the species, water content of leaf module is much more than that of other modules, the ratio of dry weight/fresh one in branch module is more than other modules in plant and its main function is to accumulate dry matter, old branch ratio in plant modules is the biggest and its function is also the biggest for supporting and developing plant growth in space and time.The plant biomass distribution at different high positions above ground is very different, the biomass of A. ordosica krasch. above ground is mainly concentrated at 0～50 cm high and is biggest value at 30～40 cm high, the biomass of A. arenaria D.C. is located at 10～100 cm high and is biggest value at 70～80 cm high. The distance between two branch layer of A. arenaria D.C. is bigger than that of A. ordosica krasch., the total branch number of A. arenaria D.C.is less than A. ordosica krasch..The wind-break and sand-fixing effect of two species is obvious, the wind speed at 20～50 cm above ground and distance of 0～300 cm from plants to the measuring points is reduced remarkably, especially, wind speed reduction at 20 cm high is the most remarkable and is the lowest wind speed at the distance of 50 cm to plants, and after that the wind speed is recovered gradually.The wind speed profile of two species are similar, the degree of wind speed reduction of A. ordosica krasch. is more obvious than that of A. arenaria D.C.. The wind-break and sand-fixing effect of the communities is obvious, especially to the ground surface. The wind speed at 20 cm high above ground in semi-fixed and fixed sandy lands comparison to the shifting sandy land is reduced 76.5% and 86.0% individually, and reduced 58.7% and 56.3% at 200 cm high above ground. When the wind speed at 200 cm high above ground in moving sandy land is 6.5m·s-1, no wind erosion happens in fixed sandy land, transported sand quantity at semi-fixed sandy land is 1.83 g·cm-1·h-1, it is 3.2% of 57.18g·cm-1·h-1 at shifting sandy land.
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