Abstract: Objective The research was designed to investigate the environmental radioactive concentration and the changes in the incidence of birth defects in Haining city of where Qingshan phase I nuclear power station of 300,000 kW unit (hereafter referred to as Qingshan phase I unit) had been in normal operation for more than 10 years (from 1992 to 2003)．Methods Data on the environmental radioactive concentration and birth defects before and since normal operation of Qingshan phase I unit in the city of Haining were collected．Streets and the administrative regions were taken as investigated units and they were grouped based on different radius distance from the site of Qingshan nuclear power station at equal kilometers．Data on the environmental radioactive concentration and birth defects before and since normal operation of Qingshan phase I unit in the city of Haining were analyzed using analytical epidemiological methods．Results Data analysis showed that the mean radiant intensity in the outdoor environment in the city of Haining before and after Qingshan phase I unit operation were(6.17±0.56)x10-8Gy/h(in 1991)and(7.92±0.77)×10-8Gy/h (in 2002)，respectively．Water quafity detection in 2002 revealed that mean concentrations of radionuclide strontium-90 and cesium-137 were 4.41 mBq/L and 1.26 mBq/L respectively．The 10一year mean incidence of birth defects from 1993 to 2003 in the city of Haining was 9.24‰．Conclusion The air absorbed gamma-radiation dose rate in the city of Haining is with the fluctuation range of natural radiation background．Compared with the mean concentration of radionuclide strontium-90 and cesium-137 before Qingshan phase I unit operation，there is no significant increase in the mean concentration of the 2 kinds of radionuclide．There is no significant increase in the mean annual incidence of birth defects after Qingshan phase I unit operation．Analysis of the subjects grouped based on different radius from the site of Qingshan nuclear power station at equal kilometers finds no significant difference in the incidence of birth defects between groups at different distances from the station．