Abstract: ObjectiveThe relationship between high temperature,summer drought and flowering habits of indica-ja-ponica cytoplasmic male sterile(CMS)lines was studied,and CMS lines of good flowering habits under high temperature and summer drought were screened in order to provide theoretical basis for application of new sterile lines and improve-ment of local germplasms.MethodFive japonica-cline and five indica-cline male sterile lines were sown in field at di-fferent times to make sure that all tested lines underwent high temperature and summer drought during flowering stage. These tested lines were comprehensively evaluated based on flowering dynamics of single panicle,anthesis duration of single panicle and whole plant,and exerted stigma rate.ResultThe results indicated significant differences with respect to flowering habits among tested lines. Under high temperature and summer drought conditions,the differences in flowering habit were mainly due to variety type. CMS lines 6466A,6474A,805A and 650A had advantages in earlier flowering peak,longer anthesis duration of single panicle and whole plant,and higher exerted stigma rate and stigma vitality. The flowering peak of 6466A was during 10:31-12:00,1.5 h earlier than that of G46A. The exerted stigma rate of 6474A was high,reaching 78.16%. 650A had the longest anthesis duration of whole plant which was up to 17.2 d. 805A had high stigma vitality and long lasting time of stigma.ConclusionCMS lines 6466A ,6474A ,805A and 650A have good flowering habits under high temperature and summer drought conditions. These lines can be used as parents for breeding under high temperature and summer drought conditions and applied in improvement of germplasm resources.