Objective To Investigat the superovulation effect in specific pathogen-free mice influenced by age,stock and season.Method We gave superovulation treatment to BALB /c and Km mice aged from 4 to 10 weeks in spring,summer and winter respectively.Statistics were done based on the rate of vaginal plug and ovulation,the number and the type of embryo acquired in day 3.5.Result None of the 3 factors we investigated have an effect on the rate of vaginal plug in specific pathogen-free BALB/c and Km mice.Otherwise these factors have a certain effect on the rate of embryo produced,the number and the type of embryo in specific pathogen-free BALB /c and KM mice.Conclusion Using specific pathogen-free BALB /c mice aged from 9 to 10 weeks in the superovulation experiments may give a satisfied number embryo in day 3.5,while the proper age of Km mice ranges from 4 to 10 weeks.Also,superovulation treatment in specific pathogen-free mice should be done in spring or summer,as it could give you a fine result.