Abstract: ObjectiveTo establish a risk assessment index system for outbreak of infectious diseases after natural hazard.MethodsTwo rounds of Delphi consultation were held among 30 experts on infectious disease prevention and control to determine the first-level and second-level indexes, and the index weights.ResultsThe active coefficients of specialist authority were 96.67% (29/30) and 100.00%(30/30) in the two round consultations, respectively. The authority coefficients of experts ranged from 0.65 to 0.95 and the mean value was 0.83. The mean values of the 7 first-level indexes and 71 second-level indexes were 4.12-4.88 and 3.14-4.76, respectively. The coefficients of variation were < 0.18 for the first-level indexes and < 0.30 for the second-level indexes. Kendall's coefficients of concordance were 0.334 for the first round of consultation and 0.478 for the second round.ConclusionRisk assessment index system for outbreak of infectious diseases after natural hazards established in the study is reasonable and comprehensive, covering the main factors influencing the occurrence of infectious diseases after natural hazard.