Soil water potential is one of the main environmental factors which are essential for seed germination and seedling establishment. Generally, germination rate increase linearly with water ability and germination percentage decrease with water potential. In this study, in order to evaluation the Onobrychis scrobiculata reaction to different water potential (drought) stress , some of germination character of this species influenced by 6 water potential level. The obtained results showed that both germination percentage and germination rate decreased when water potential increase. Increase of drought stress resulted in increase the germination time.