The formation and evolution of vegetation sowed by airplane in the Alxa Desert is closely related to the amount and distribution of rainfall in growing season. The results in this study showed that the percentages of callogonum mongolicu,Psammochloa mogolica and Artemisia sphaerocephala in this area were higher than other species when the monthly rainfall is more than 65 mm during planting period. Furthermore,the important values were 64.5%、61.59% and 23.67% respectively and the biomass was 2038.20 kg/hm². The percentages of Artemisia aphaeocephala and Peganum nigellastrum in this area were higher than other species when the monthly rainfall is less than 40mm during planting period. Their important value were 65.51% to 66.58% and 35.71% to 46.11% respectively and the biomass was 1827.30 to 1834.65 kg/hm². In additionally,species richness also varied with different seasons in this area. The important value and the biomass of A. sphaerocephala increased,but the percentages of A. sphaerocephala were stable,which indiacted that A. sphaerocephala were adaptable during growing season,from June to September. For Calligonum mongolicum,the important value and biomass increased from June to August,but decreased in September. However,it is relatively stable among all species. The biomass and the important value of P. mogolica decreased with seasons,which indicated the degradation of P. mogolica. Above results showed that planting Artemisia sphaerocephala and calligonum mogolica is an effective measure for controlling degradation in the Alxa Desert.