Abstract: The plant characters and the microspore development during the sensitive period of pollen fertility alternation in the thermo-sensitive genic male sterile 5460(TGMS 5460) were observed under different temperatures and photoperiod in nature and in the phytotron.The main results showed that,(1)It was the sensitive period of pollen fertility alternation when the rice plant grown in the status of 0.1～8.6cm length of the flag leaf collar and 7.6～14.5cm length of the young panicles as well as 9.0～13.4 days before heading,in which the microspore developed from tetracytes to early binucleus.In the sensitive period treating with high temperature and long photoperiod only for one day could cause the sterile of pollen fertility,that for 5 days could make the complete sterile of pollen fertility,(2)Outside the sensitive period,temperature and photoperiod did not have obvious effects on pollen fertility.