Abstract: P.cornutum and P.dolabratum were used as test materials.The response of P.cornutum and P.dolabratum to high temperature was studied by artificial simulated drought test.The physiological and ecological adaptability of P.cornutum to high temperature in desert, as well as the change of chlorophyll fluorescence under high temperature stress and its response mechanism to high temperature were discussed, in order to provide reference for the industrial cultivation of P.cornutum.The results showed that the seedlings of P.cornutum and P.dolabratum showed slight heat injury symptoms, P.dolabratum 40 ℃/24 hours, P.cornutum 45 ℃/2 hours; heat treatment directly led to plant death, P.cornutum 50 ℃/24 hours, 60 ℃/3 hours; P.dolabratum 45 ℃/24 hours, 50 ℃/8 hours and 60 ℃/2 hours.When the temperature increased to 40 ℃,through the maximum fluorescence yield Fm and variable fluorescence Fv analysis, the electron transfer of P.cornutum and P.dolabratum through PSⅡ was significantly inhibited, and the number of QA oxidation state in PSⅡ reaction center decreased, so that the ability of QA → QB to transfer electrons decreased.When the temperature increased to 60 ℃,the initial fluorescence（Fo） reflected that the PSⅡ reaction center was irreversibly deactivated.The 60 ℃ of P.cornutum was 1.51 times that of 30 ℃,and the P.dolabratum was 3.07 times, indicating that the PSⅡ reaction center of P.dolabratum was more seriously damaged than that of P.cornutum at 60 ℃.At the same time, the changes of Fv/Fm,Fv/Fo and Fm/Fo were consistent.The temperature of 50 ℃ decreased significantly, and the temperature of 60 ℃ was close to 0.The photosynthesis of P.dolabratum began to decrease significantly at 40 ℃,indicating that 50 ℃ significantly affected the photosynthesis of P.dolabratum,while 40 ℃ significantly affected the photosynthesis of P.dolabratum,and the photosynthesis of both was almost lost at 60 ℃.Based on the analysis of heat injury symptoms and chlorophyll fluorescence dynamic parameters of P.cornutum and P.dolabratum seedlings, both of them were resistant to high temperature, showing adaptability to the sand area environment, and also indicating that P.cornutum was more resistant to high temperature than P.dolabratum.