ObjectiveTo determine the dose of butorphanol at which 50％ and 95％ effective dose (ED50 and ED95) of patients inhibition uterine contraction pain on analgesic artificial abortion.Methods Twenty-six patients undergoing analgesic artificial abortion were sequentially given different doses butorphanol so that the ED50 and ED95 could be determined by up-and-down sequential test.Anesthetic depth was observed when giving propofol with 200 mg/min speed,uterine contraction pain at awaking immediately,10,20 min after awaleing.Data was analyzed by Probit regression analysis for calculating ED50 and ED95..ResultsButorphanol could restrain uterine contraction pain on analgesic artificial abortion and the ED50 was 246 μg with the 95％ confidence interval of 201 μg to 281 μg,the ED95 was 324 μg with the 95％ confidence interval of 287 μg to 548 μg.ConclusionED50 and ED95 value can be expected as a parameter to optimize analgesic artificial abortion.