Objective To investigate the indices of physiological development and reproductive performance in FVB. KO and FVB. Method 40 seeds FVB. KO and FVB (20 male and 20 female mice，aged 10 weeks) were chose and monogamously mated. After natural delivery，the research tested the reproductive performance and indices of physiological development such as pinna detachment，body hair sprouted，incisor eruption eye opening. Result The reproductive performance and indices of physiological development but rate of male and female in FVB. KO and FVB were no difference.The rate of male and female in FVB. KO was lower. Conclusion Fmr1 has no effect on behavioral development and reproductive performance in mice. But it maybe has some effects on rate of male and female in mice.