Abstract: In order to study effects of different hormones on estrus induction and farrowing effect of bitches, 110 bitches without estrus for a along time were divided into five groups, among them group Ⅰ was treated with intramuscular injection of PMSG; group Ⅱ was treated with intramuscular injection of the combination of PMSG and HCG; group Ⅲ was treated with intramuscular injection of the combination of PMSG and LRH-3; group IV was treated with intramuscular injection of the combination of PMSG, PGF2α, E2 and LRH-3; group V was control group. Results showed that, as for estrus, group IV had the best effect, and showed high reaction in degree of vulva swelling, flowing-blood secretion and keratinization degree of vaginal epithelium; the estrus rate of group Ⅳ was 32%, 28% and 20% more than that of group Ⅰ, group Ⅱ and group Ⅲ respectively （P〈0.01）. Group IV had the highest conception rate of 76% which was 35%, 20.4% and 10% more than that of group Ⅰ, group Ⅱ and group Ⅱ respectively; group Ⅳ had very significantly difference with group Ⅰ and group Ⅰ, and had significantly difference with group Ⅲ. The litter size of group IV was 130 which was 92, 74 and 45 more than that of group Ⅰ , group Ⅱ and group Ⅲ, respectively （P〈0.01）. Control group wasn＇t treated with any drug, and it had the lowest estrus rate （10%）, and its conception rate was 0. It is suggested that the combination of PMSG, PGF2ct, E2 and LRH-3 had the best effect of estrus induction, and both conception rate and litter size were better than those of single use or the other combinations.