Objective To study the effect of FSH and LH on superovulation in KM mice.Method 48 mice were divided into 4 groups,which received FSH 3 IU,6 IU,9 IU and 12 IU i.p.,respectively,quadrifidly and in a decreasing sequence.48 hours later,LH in a dose of 3 IU,6 IU,9 IU and 12 IU was injected.The female mice were combined with male mice in one cages,and were checked for embolus the next morning.Embryos were washed out 48 hours later.Result The rate of embolus visualization was 79.17%(38/48).The average of washing out embryos was 5.67(68/12),13.00(156/12),29.17(350/12),11.50(138/12) embryos per mouse according to the used hormones: 3 IU FSH 3 IU LH,6 IU FSH 6 IU LH,9 IU FSH 9 IU LH and 12 IU FSH 12 IU LH,respectively.Conclusion The protocol using 9 IU FSH 9 IU LH is the most effective to induce superovulation in KM mice among all schemes used in this study.