The main problems about research and application of twoline hybrid rice were reviewed, including the confusional name and classification of male sterile lines, the unclear characterization of responses to photoperiod and temperature and the unsuitable site selection for seed production of male sterile line and hybrid rice. In order to efficiently and accurately use photo(thermo)sensitive genic male sterile (PTGMS), four types, including PTGMS, TGMS, negative PTGMS and negative TGMS were proposed. A new idea for explaining the mechanism of sterility in PTGMS rice was proposed. The transition from sterile to fertile was involved in cooperative regulation of majoreffect sterile genes and the photoperiod and/or temperature sensitive ones for development. The minoreffect genes, with accumulative effect on sterility, were the important factors that affect the critical temperature of sterility transfer. In order to make better use of PTGMS, the characterization of responses to photoperiod and temperature of PTGMS should be made. The identification method for the characterization responding to photoperiod and temperature of PTGMS was also put forward. The optimal ecological site for seed production could be determined according to the historical climate data and the requirements for the meteorological conditions during different periods of seed production.