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.