Abstract: Effects of air temperature and relative humidity influence on grain filling and percentage of unfilled grains with the late rice of 1996~2005 were studied in the paper. The result shows that air relative humidity has no distinct influence on grain filling. It is significant that higher temperature during stage of grain filling brings on higher velocity of grain filling. The days whose daily maximum of air temperature exceed 30℃ per-day have insignificant influence on blighted grain rate of rice. But the days whose daily maximum of air temperature exceed 30℃ per-day during booting and heading stages have very significant influence on percentage of unfilled grains. Finally some suggestions on how to prevent disaster of high temperature are put forwards in the paper.