Abstract： Objective To determine caregiver willingness to vaccinate left-behind and non-left-behind children in rural areas with non-Expanded Program on Immunization(EPI)vaccines and factors influencing willingness.Methods We enrolled caregivers of left-behind and non-left-behind children aged 1-6 years from rural areas in two provinces of China for a questionnaire-based survey and analyzed their willingness to vaccinate children with non-EPI vaccines and factors influencing willingness.Results Rates of willingness to vaccinate left-behind and non-left-behind children with non-EPI vaccines among caregivers were 85.53％(721/843)and 86.03％(751/873),respectively.Multivariate logistic regression analyses showed that willingness was high among caregivers of left-behind children who had high annual family incomes per capita(5-19 vs＜5 thousand yuan:OR=2.56,95％CI:1.54-4.27;≥20 vs＜5 thousand yuan:OR=2.85,95％CI:1.47-5.51),when caregivers knew about effectiveness and necessity of non-EPI vaccines(OR=2.62,95％CI:1.66-4.13;OR=4.58,95％CI:2.92-7.19),and when migrant parents were concerned about children's vaccination and subsidized their family(OR=2.21,95％CI:1.10-4.43;OR=2.20,95％CI:1.37-3.52).Willingness was high among caregivers of non-left-behind children when caregivers knew about differences between EPI and non-EPI vaccines and necessity of non-EPI vaccines(OR=3.61,95％CI:1.76-7.40;OR=7.58,95％CI:4.95-11.61).Conclusions Caregivers had high willingness to vaccinate left-behind and non-left-behind children with non-EPI vaccines in the surveyed areas.We should strengthen health education on knowledge about non-EPI vaccines to promote non-EPI vaccination of children.