Under the case of the artificial low temperature and drought, the lea f fluorescence parameters (Fo, Fm, Fv/Fm) and Photosynth esis rate are determined . The results show that the low temperature or drought decreased photochemical c onversion effect, their relationship can be expressed as follow:Y=0.002X2-0.0055X+0.8032 There: Y is photochemical conversion effect; X is tempera ture. The low temperatu r e decreased photosynthesis rate. The photosynthesis rate decreased by 27.8% when temperature decreased from 25℃ to 15℃.When the soil moisture decreased from t he treatment 5 to the treatment 1, during different temperature Photochemical conversion effect decreased by 1%～8%, and Photosynthesis rate decreased by abou t 80%. The negative effect of the low temperature combining with drought on phot ochemical conversion effect and photosynthesis rate was far greater. The decreas ing scale of photochemical conversion effect reaches 2.5 times, and the photosy nthesis rate was increased by about 15%. The photochemical conversion effect and photosynthesis rate was remarkable positive relation.