Objective To compare the effect of mifepristone and levonorgestrel using in emergency contraception. Methods 206 patients with no protective sex required emergency contraception within 72h were randomly divided into group1(n=136) and group 2(n=72), in group 1 , single oral mifepristone 25mg; in group 2, oral levonorgestrel 0.75mg and once more 0.75mg after 12h. Results There were two pregnancy in group 1 and three pregnancy in group 2, the rate of failure was 1.47% in group 1 and 4.29% in group2, the rate of effective contraception was 84.1% in group 1 and 61.3% in group 2, the rate of side reaction was 7.53% in group 1 and 17.14% in group 2. Conclusion Both mifepristone and levonorgestrel are effective emergency contraceptives，but mifepristone for emergency contraception is better than levonorgestrel.