Abstract:TP-2 is a spontaneous semi-sterile mutant of TP309 which is a variety of rice (Oryza sativa). The filaments of small flower are slender, the anthers are shriveled in white and transparent, the development of female organ is normal. Pollen viability shows that the pollen viability of mutant is 57.599%, much lower than that of control group (94.177%), the pollen grains in TP-2 pollensac 436, much lower than that of control group (798). Paraffin section shows that the development from microspore mother cell to the end of meiosis on TP-2 mutant rice is normal, compared with the normal strains in the form. However, in the early microspore formation, rapid melting of tapetum, the process of microspore development lack of nutrition can not develop normally, resulting in a small dry spore. It has irregular shape, while some small spores have broken ablation phenomenon. May be the main reasons of abnormal development of small spores on TP-2 rice is the tapetum does not degrade normally. The observation provides basic material to mutant infertility of TP-2 and lays the foundation of TP-2.