The forecast of sterile alteration for the temperature-sensitive genic male sterile (TGMS) line in two-line hybrid rice seed production was traditionally based on screen temperature determined by weather station. The article put forward a new approach based on plant temperature,which was more exact and direct than the traditional method. The result of the simulation of the self-seeded setting rate of a widely used TGMS line,Peiai64S,by several temperature parameters and durations,showed that the fertility was directly affected by the plant temperature at a height of 20 cm or the air temperature around it in three days duration. Using the stem temperature of three days at a height of 20 cm as the simulation parameter,the fertility of Peiai64S had the maximum,minimum and optimum temperatures as 22.8,21.7 and 22.5°C,respectively,whereas 23.2,21.5 and 21.8°C when using the air temperature of three days around the height of 20 cm as the parameter. Such temperature indices can be used to conclude the sterile alteration of TGMS for safeguarding seed production of two-line hybrid rice. The article also established a statistic model to conclude plant temperature by water temperatures at inflow and outflow,and air temperature and cloudage from weather station. The forecast of sterile alteration for the temperature-sensitive genic male sterile (TGMS) line in two-line hybrid rice seed production was traditionally based on screen temperature determined by weather station. The article put forward a new approach based on plant temperature, which was The result of the simulation of the self-seeded setting rate of a widely used TGMS line, Peiai 64S, by several temperature parameters and durations, showed that the fertility was directly affected by the plant temperature at a Using the stem temperature of three days at a height of 20 cm as the simulation parameter, the fertility of Peiai64S had the maximum, minimum and optimum temperatures as 22.8, 21.7 and 22.5 ° C, respectively, whereas 23.2, 21.5 and 21.8 ° C when using the air temperature of three days around the height of 20 cm as the parameter. Such temperature indices can be used to c onclude the sterile alteration of TGMS for safeguarding seed production of two-line hybrid rice. The article also establishes a statistic model to conclude plant temperature by water temperatures at inflow and outflow, and air temperature and cloudage from weather station.