Abstract: The variation of rice leaf temperature with ambient air temperature and irradiance intensity imposed on the leaf surface is discussed based on the experimental data in a controlled environment chamber. The heating effects of irradiance on leaf temperature will change the patterns of photosynthetic response to light intensity. According to the rectangular hyperbola photosynthetic model, the rice leaf photosynthetic character in different environment conditions is simulated. The results show that when the air temperature is less than the temperature suitable for photosynthetic physiological process, the heating effects raise the leaf temperature, thereby improving the photosynthetic capacity. Otherwise, the effects are contrary to the results above.