Abstract: To establish a rat model of ovarian hyperstimulation syndrome,a total of 18 immature female rats were randomly divided into three groups：ovarian hyperstimulation group,superovulation group and control group.According to our modification of Ujioka method, six rats in ovarian hyperstimulation group were given a subcutaneous injection of 10 IU pregnant mare serum gonadotropin （PMSG） in 0.lml 0.9% saline for 4 consecutive days, then given 100 IU human chorionic gonadotropin （HCG）in0.1ml 0.9% saline on the fifth day（26th day of life）.In superovulation group,six rats were given 10 IU PMSG at the time indicated above on the 24th day of life，and were given 10 IU HCG 48 h later （26th day of life）.In control group，the rats were given the same dosage of 0.9% saline for 4 consecutive days, from the 22nd day to 26th day of life. 72 h after HCG injection, 0.1ml 1% EB was injected into each rat by tail vein in order to determine the peritoneal capillary permeability.30 min after the last injection , we found that ovarian weight,peritoneal EB level and ascitic score of ovarian hyperstimulation group were significantly higher than those of superovulation group and control group（P＜0.001respectively）.These results demonstrated that the establishment of rat model of ovarian hyperstimulation syndrome was successful and may be useful for research on the pathogenesis of the ovarian hyperstimulation syndrome in the future.