Abstract: Objective To observe whether current exposure to radiation caused health damage of radiation workers in a nuclear power plant. Methods The data of micronuclei of peripheral blood lymphocytes of 1 822 radiation workers from 2010 to 2014 were evaluated. Results The mean number of micronucleus per 1 000 cells varied from 0.51 to 1.33 during these 5 years with average of 0.9. The abnormality varied from 0.22% to 1.70% with the average of 1.01%. There was a trend that both number of micronucleus and abnormality gradually decreased along with time(χ² _trend =125.89,15.77,P<0.01), but no significant increasing trend of abnormality was noted among different radiation workers with increasing exposure time(P>0.05). Conclusion The figures of micronuclei of peripheral blood lymphocytes were relative higher compared with foreign reports. More attention should be given to these radiation workers in this nuclear power plant.