Abstract: FHS of special fertility is got from the offsprings of the rice 99-02 which has been irradiated by low energy ion beam. In order to reserch the fertility and fertility trasition Conditions, the fertility characteristic of FHS is studyed through different planting time and under different temperature. The results suggest that the fertility of FHS Is steady from the last ten days of July to the first ten days of August,which is it’s fertility period; the middle ten days of August to the last ten days of August is it’s fertility trasition period, during which it is partly fertile period；The days from the last ten days of August is it’s completely sterile period.Consulting on the weather datum and the temperature trasacting the rice with which, the coclusion shows that the fertile critical temperature of FHS is 27~28℃, the sterile temperature is 23~24℃.