Abstract: A total of 90 rats were divided into five groups (n=18) and immunized i.m. with 10, 50, 100μg inhibin eukaryotic expressing plasmid fused with HBsAg gene (pCIS), 50μg vector (pcDNA3.1) or 100μL 0.85% saline. A booster was given 20 days later, and 12 of rats in each group were given twice boosters. The results showed that the boosters raised the level of antibody against inhibin. There were 6.9 and 7.5 more mature follicles in 100μg group after twice and three times immunizations of pCIS than that in the control(P<0.05). The mature follicles after three times immunizations were remarkably more than that after twice immunizations(35.2±2.73 Vs. 31.0±0.92，P<0.05). After three times immunizations of pCIS, the placentas and litter size in total trials were more than that in the control (P>0.05), and positive group more than negative group (P<0.05). After three times immunizations , the correlation coefficient between the positive antibody and the mature follicles was 0.45（P>0.05）, while it got to 0.77（P<0.05）between the positive antibody and the placentas. The level of FSH on estrus and after parity in total trials was higher than that in the controls, which in positive rats was higher than that in negative rats, especially after twice immunizations (P<0.01). In conclusions, inhibin gene immunization can stimulate follicular development of rats and raise the level of plasma FSH, which set up the basis of inhibin gene immunizations on large animals.