To detect the toxicity of neonatal exposed to methylmercury chloride on the adulthood reproduction，as well as early growth and development in rats and the intervention of Lycium barbarum polysaccharide. Methods：Sixty SD of 7 d rats were randomly divided into saline Control，MMC，MMC+LBP，LBP. The natural development，weight growth and fertilities were observed. Healthy pregnant female rats and MMC exposed neonatal rats and were also observed. Results： 1) Compared with the control group，the rats in MMC group was dropping，inactivity，loss of appetite; 2) The weights of rats in MMC group grew slower than in control rats with the exposure time dependently; 3) MMC group were infertility after exposure to the methyl mercury. There remained offspring in MMC+LBP group and their after-born death rates were higher than that of the control group，with low birth weights and low survival rates; 4) The weights in MMC+LBP rats were significant lower (P<0.01) than that in in control and LBP group; 5) The MMC exposed pups influenced the next reproduction of the female rats. Conclusion： Methylmercury chloride has development and reproductive toxicity effects on rats. Lycium barbarum polysaccharides have potential protection against the toxicity roles.