Abstract: This experiment is dealing with the high temperature injury from milky stage to ripening stage of early rice, and is in the phytotron under natural light. The main purpose is to study the effect of the different temperatures and their duration on fruiting during from milky to ripening stage. The early milky stage (6–10 days after heading) is more sensitive to the influence of high temperature on the percentage of ripened grain. The late milky stage (11–15 days after heading) is more sensitive to the influence of high temperature on the weight of kilograin. The cause of the decrease of output effected by 35 ℃ is mainly due to the decrease of weight of kilograin and the percentage of ripened grain from milky to ripening stages, but little influence on the percentage of empty seeds. The main cause of the decrease of kilograin weight and percentage of ripened grain is due to too early decrease of food accumulation, but not to sharp decrease of the assimilates.