Photoperiod sensitive genetic male sterile (PGMS) rice is sterile mutant controlled by photoperiod. A PGMS mutant 920S was sterile grown under long-day (LD) photoperiod (14 h light/10 h dark) but fertile grown under short-day (SD) photoperiod (10 h light/14 h dark). Proteome analysis revealed that 12 protein spots were differentially expressed in the spikelets of 920S plants either treated with LD or SD photoperiod. Among these proteins, three proteins including chlorophyll a/b binding protein, vacuolar ATPase β-subunit,~;α-tubulin and an unknown protein were more than three-fold abundant in the spikelet of the SD-treated plants than those of the LD-treated plants. On the other hand, eight proteins including acetyl transferase, 2, 3- biphosphoglycerate, aminopeptidase N, pyruvate decarboxylase, 60S acidic ribosomal protein and three unknown protein spots were more abundant in the spikelets of the LD-treated plants than those of the SD-treated plants. The results suggest that the observed proteins may be involved in sterile or fertile pollen development under LD or SD photoperiod respectively in the PGMS mutant rice.