The fertility inheritance and expression under the influence of different genetic background of four Photo-Thermo Sensitive Cenic Male Sterile Rice were studied .The results indicated that the fertility of W6154S, W7415S, N12S and N18S was controlled by two pair of nuclear recessive genes, but their expression and genetic mechanism were very complicated due to the great influence of various genetic background. By thoroughly analyzing the fertility segregation of F2, F3 population, the hypothesis, "incomplete dominance and dosage effect of restorer genes", was put forward and the poymorphism of fertility segregation was also discussed in this paper.