Abstract:Lathyrus sativus L. was used as experimental material and treated by PEG6000. The results showed that at the beginning of stress(0~48 h), stomatal conductance(Sc) and transpiration(Tr) decreased sharply, while net photosynthesis rate(Pn) and water use efficiency(WUE) fluctuated at a certain level. But these photosynthetic indexes recovered near to normal soon after 48 h. Moreover, the content of free proline showed a significant elevation, especially at 48 h and 60 h. When REC increased nearly 50 percent of control, proline had accumulated 14 times more than the control. All data above suggests that the seedlings of L. sativus L. could alleviate its stress damage by declining Sc/Tr and accumulating plenty of proline, which might be some of drought-resistant mechanisms.