Objective: To explore the cumulative effects of unintentional injury among children in rural area, in order to provide information for early intervention of unintentional injury. Methods: Through multistage clustering sampling method, 2 109 primary caregivers of students from 8 rural primary and elementary schools of Heilongjiang Province were recruited. Strengths and Difficulties Questionnaire (SDQ), Injury Behavior Checklist (IBC), Perceptions of Risks and Hazards were used to collect as the risk factors, while Perceptions of Risks and Hazards (PSAPQ), Home Observation for Measurement of the Environment (HOME) and Knowledge, Attitude and Practice for Children Unintentional Injury (KAP) were also used as the protective factors. Risk factors index (RFI) and protective factors index (PFI) were computed in the study. Results: The severity of unintentional injury were positively correlated with SDQ, IBC and perceptions of risks and hazards(r=0.15, 0.23, 0.12, P<0.01), and were negatively correlated with HOME, PSAPQ and KAP(r=-0.25, -0.14, -0.09, P<0.01). Hierarchical linear regression showed that the total scores of SDQ, IBC and environmental of HOME predicted the severity of unintentional injury which could explain 34% variant of unintentional injury. It also indicated that the severity of unintentional injury were positively correlated with RFI (β=0.21) and negatively correlated with PFI(β=-0.18), the interaction was significant(β=-0.11,R2=0.31)(P<0.01). Conclusion Both risk and protective factors of unintentional injury have cumulative effects on the severity of injury among rural children. The relationship between risk factors and injury could be mediated by protective factors.