Abstract: The experiment aims to investigate the effects of body conditions and pregnant mare serum gonadotropin（PMSG） on the synchronization of estrus in sheep.A total of 60 ewes with good body condition were randomly divided into group A and group B, and 120 ewes with poor body condition were randomly divided into group C and group D. Groups A and group C were injected with intramuscular injection of 400 IU PMSG, while groups B and D were injected with intramuscular injection of 330 IU PMSG. The results showed that the effect of intramuscular injection of 400 IU PMSG was better than that of intramuscular injection of 330 IU PMSG（P＜0.05）, and the effect of estrus synchronization in good body condition was better than that of in poor body condition（P＜0.05）. It could be concluded that the body condition of ewes would significantly affect the effect of synchronous estrus, and appropriate application of reproductive hormones could improve the synchronous estrus rate of sheep.