Abstract: Nine japonica restoring lines with different background and growth duration were used to hybridize with Nongken 58S, during 1997～1999, the authors explored the number and allelism of major genes to restore the fertility of photoperiod sensitive genic male sterile line Nongken 58S.The results showed that, all of restoring lines tested possessed one or two pairs of dominant genes.Furthermore, T984 had one pair of restoring genes as Nongken 58 Sdid, however, all of the other seven lines conferred two pairs of dominant fertile restoring genes, it suggested that, Nongken 58 Spossessed two pairs of recessive male sterile genes, the genetical background modify the disjunction and expression of minor genes on well.