Abstract: This paper simulated drought stress conditions by adjusting the sucrose concentration and forming different osmotic potential in the MS medium, and through the testing, studied change rule of malondialdehyde (MDA), soluble sugar content, peroxidase (POD) activity and proline content of Ammopiptanthus mongolicus ( Maxi m) Cheng.f’s tube culture under the condition. The results show that with the increase of drought stress, the content of MDA and soluble sugar increases significantly, and activities POD, proline content roses at the beginging and then declines. Therefore, ψπ=-1.540Mpa and stressing 72h is the tolerate threshold of stress,and it causes the obvious decline of proline content and POD activities, and seedling growth is affected seriously.