The study aims to assess the change of peripheral blood cell numbers following protracted low-dose radiation exposure among medical radiation workers.A cohort of 375 Chinese medical workers were followed for 5 years (2015-19) and recorded the changes in blood cells and cumulative doses. T-test, least significant difference-T test, variance analysis and correlation analysis were utilized in this study.Compared with the control group, the white blood cells, hemoglobin counts and the ratio of eosinophils in the study group showed a downward trend. The differences in blood cells between groups were mainly found in the number of red blood cells. In a short cumulative time, such as 1 or 3 years, a correlation between the cumulative dose and the quantity of blood cells was detected, but not at 5 years.There is no significant difference in the blood cell counts between different types of work, and the long-term cumulative dose has not been statistically correlated with the number of blood cells. So that the number of peripheral blood cells can no longer be used as a good indicator of radiation damage.