The effects of drought stress，simulated using polyethylene glycol(PEG-6000)( －0． 03，－0． 10，－0． 24，－0． 42，－0． 65，－0． 94 MPa)，were investigated on the germination of the seeds and the growth the seedlings of two plant species，Sophora alopecuroides L and Swainsonia salsula (Pall． ) DC． which are dominant local species on the desert edge in the middle of Hexi Corridor． The results show that with increasing stress from PEG，water absorbing rate，germination percentage，germination index，vigorousness，seedling height，root length，and saturated water content of both species decreased，whereas dry weights of seedling and root，and crown-root ratio increased and then decreased． This indicates that appropriate drought stress might improve the drought resistance and then the quality of the seedlings． Possible causes for this adaptation to drought stress by the two species were explained and discussed．