Peiai 64S (Oryza sativa L. subsp. indica), is a thermo-sensitive genic male-sterile (TGMR) rice. High temperature causes sterile pollens at the microsporogenesis stage. The anther morphology and the calcium precipitate were investigated in the fertile and sterile anthers of Peiai 64S under low or high temperature. There were more small vacuoles, more calcium precipitates and less mitochondria in the sterile pollen mother cells than those in the fertile pollen mother cells. More calcium precipitates were located in the epidermis, endothecium and tapetum of the sterile anther than in those of the fertile anther. Longitudinal inner cell wall of the sterile anther became thicker than that of the fertile anther at the dyad stage and uninucleate pollen stage. Some large vacuoles appeared in the tapetal cells of the sterile anthers at the early uninucleate pollen stage. All of the sterile pollens possessed malfunctioned exine. The results proposed that the abnormalities of pollen mother cell, the tapetum and the pollen exine, and more calcium precipitates in TGMR rice Peiai 64S under high temperature were related with the pollen abortion.