Abstract: In order to find the best sowing date of single-cropping late rice in Hunan, and to avoid high temperature harm to rice in pollen mother cell meiosis stage and heading stage, the effects of air temperature of different rice stage in pollen mother cell meiosis stage and heading stage on seed setting rate and yield were studied by different sowing date in plot. The harm of high temperature to rice in Hunan province also was investigated. The results showed that the best sowing date of the long-growing –period-single-cropping late rice was on 20th May, and to the short-growing-period-single -cropping late rice, the best sowing date was on 30th May in the center of Hunan. The safety pollen mother cell meiosis stage of panicle development stage and heading stage were after 13th Aug and the last ten days of August in both sort of rice, respectively.