The cytoplasmic male sterile line CMS102 and the restorer line ST-8 of capsicum were used as materials. The anther cytological morphology of flower buds in sporogenic stage, microspore mother cell stage, microspore meiosis stage, tetrad stage, uninucleate microspore stage, binucleate microspore stage and pollen maturity stage were observed. The contents of physiologically active substances related to fertility in flower buds in microspore meiosis stage, tetrad stage, mononucleate microspore stage and binucleate microspore stage were determined. The results showed that CMS102 abortion occurred in the tetrad stage, and the tapetum overexpanded and squeezed the tetrad, so that it could not normally develop into monokaryon microspore, which belonged to sporophyte sterility; the contents of soluble protein and free proline in CMS102 buds were lower than those in the restorer lines, while the contents of soluble sugar, MDA content and POD enzyme activity in CMS102 materials were higher than those in restorer lines. The genetic segregation population of F2 was constructed and its fertility was investigated, and the fertility of CMS102 was analyzed. It was found that the fertility restoration of CMS102 materials was regulated by a pair of dominant genes.