Using the critical temperature and daylength as indices derived from the fertility alteration model of photoperital-sensitive genic male sterile rice(PGMSR)and 1951～1988 data of daily mean temperature and theoretical daylength from 15 representative weather stations on a national basis,analysis is performed of climatological characte-istics of the fertility alteration data and the duration of the fertile and sterile periods of three male sterile lines(7001s,5088s and Annong s一1).This provides a new approach to the ananlysis of climatic basis for fertility alteration of two-lined hybrid rice and a theoretical basis for further application of sterile line crop to planting.