Abstract: The physiological response to the high temperature by 7 provenances of Simmondsia chinensis collected from both in its natural distribution area and in the introductiondomestication area was experimented with potgrown seedlings in the temperature controlled greenhouse treated with three different levels of high temperature stress. The results indicated that the different provenances showed the similar way of change in the physiological indexes under high temperature stress. The leaf water content of the all different provenances decreased and the cell membrane permeability increased under the heat stress. The POD activity of all different provenances under T1 treatment was significantly higher than that of the CK, while the SOD activity of different provenances was lower than CK under the same stress. Under the T2 treatment, the SOD activity of different provenances was higher. There was no distinct law of change in the MDA content, but with significant increase of proline content under both T1 and T2 heat treatment. Along with the development of the high temperature stress, the content of soluble protein increased at first and then decreased with the increment of heat stress degree. Under heat stress, the soluble sugar content of each provenance seedling leaves did not show consistent change trend.