The main problems about research and application of two-line hybrid rice were reviewed,including the confusing nomenclature and male sterile lines classification,the unclear characteristics of photoperiod and temperature responses and the unsuitable site selection for male sterile line and hybrid rice seed production.In order to efficiently and accurately use dual-purpose genic male sterile lines,four types,including PTGMS (photo-thermo-sensitive genic male sterile rice),TGMS (thermo-sensitive genic male sterile rice),reverse PTGMS and reverse TGMS,were proposed.A new idea for explaining the mechanism of sterility in dual-purpose hybrid rice was proposed.The transition from sterile to fertile was involved in the cooperative regulation of major-effect sterile genes and photoperiod and/or temperature sensitive ones.The minor-effect genes with accumulative effect on sterility were important factors that affected the critical temperature of sterility transfer.In order to make better use of dual-purpose lines,the charecterization of responses to photoperiod and temperature of PTGMS should be made and the identification method for the characterization of photoperiod and temperature responses of PTGMS should also be 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 the different periods of seed production.