Abstract: This paper focuses on the relation between photosynthetic rates and air temperature in A. chinense and S. grandis in the beginning, the peak and the late period of their growth. The results are as follows.For A.chinense,the relation between photosynthetic rate and temperature shows a curve of cubic function,wheweas for S.grandis it is a curve of quartic function. Compared with A.chinense,the compensation point of photosynthesis at lower temperature in S.grandis is higher,and at higher temperature,this value is lower in S.grandis than in A.chinense. But the slopes for the two curves show little difference. At different growth stages, the indices for photosynthesis mentioned above show a little change. They reach the highest values of compensation point of photosynthesis at higher temperature and the optimal temperature at the peak growth stage. Compared with the beginning stage, these values for the late growth stage are lower.At the half-saturation and near-saturation points, the air temperature of photosynthetic rate is highest in peak growth stage. At the other two stages, the late stage is lower than the beginning for the two species in the decreasing section of the curve and in increasing section of the curve for S. grandis, it is the same with the decreasing section, but for A. chinense,it is just the opposite.