Objective To characterize the growth and reproductive performance of SPF C57BL/6J mice under SPF raising conditions.Methods 40 seed mice(20 male and 20 female mice,aged 80-90 days)were chosen and monogamously mated(B S).The parameters of growth and reproductive performance were analyzed.Results It was found that SPF C57BL/6J mice were growing slower in development after weaning.The reproductive performance of mice of the second and third birth sequence was best,and that of the fifth birth was the least.Conclusion Our findings indicate that to mate and breed SPF C57BL/6J mice should not be more than 5 births.