Abstract: Migration and transference of restoring genes of hybrid rice to MS line were imitated in this study by the method of controlling pollination in order to find out the relation between the introduced restoring genes and self fruitfulness in MS line.The main conclusions were as follows:self fruitfulness in MS line is mainly caused by the introduced restoring genes, that is to say, restored or half-restored plants with the same cytoplasm as MS line have been appeared in the selfing generation and back-crossing generation of MS line.All hypotheses of so-called “back mutation”, “environmental impact” can not explain roundly why self fruitfulness occurred in MS line.

Key words: Hybrid rice, Restoring gene, MS line, Self fruitfulness