Objective Based on the calculation and analysis of the actual cost and reasonable cost of expanded program on immunization (EPI) in Zhejiang Province, this paper provides the data support for EPI. Methods The actual cost of EPI in province, cities, counties, townships and villages was investigated by filling out questionnaires. According to the relevant laws and regulations and expert estimation method to calculate the reasonable cost, makes a comparative analysis between the actual cost and reasonable cost, and makes sensitivity analysis at reasonable cost. Conclusions The actual cost of per injection in Zhejiang province total of 19.55 Yuan, of which the provincial, city, county, township, village level, the actual cost of per injection was 0.27 Yuan, 0.34 Yuan, 1.41 Yuan, 16.89 Yuan, 0.64 Yuan. The reasonable cost of per injection in Zhejiang province total of 85.21 Yuan, of which the provincial, city, county, township, village level, the reasonable cost of per injection was 0.78 Yuan, 0.92 Yuan, 10.65 Yuan, 67.96 Yuan, 4.91 Yuan. The actual cost of vaccination in Zhejiang province is 65.66 yuan lower than the reasonable cost. The single factor sensitivity analysis was carried out on the reasonable cost according to the number of employees, vaccine injection times and the working time. It was found that there was a positive correlation between vaccine injection times and the reasonable cost. The 30~50 times per day inoculation needle estimates the cost is reasonable. Conclusions The cost of grass-roots EPI in Zhejiang province is low, so the government should provide financial and staffing support to EPI in accordance with the reasonable cost, so as to ensure the sustainable development of EPI