Abstract: Objective To construct an early warning index system for major diseases in Wuhan metropolitan area according to epidemic features of the diseases,and to evaluate the index system by a case study.Methods Two rounds of Delphi experts' consultation were applied to construct the early warning index system.The indexes' weights were defined by analytic hierarchy process and experts' evaluation.Reliability,validity of the index system and the rationality of index weight distribution were evaluated in site investigation.Results The Early Warning Index System of Major Diseases in Wuhan Metropolitan Area included 3 first class indexes,9 second class indexes and 41 third class indexes.The active coefficients of experts in the two rounds of Delphi investigation were 93.75% and 100%;the familiarity degree was 0.91±0.07;the authority degree was 0.92±0.04;the Kendall W^a coefficients were 0.383 and 0.500.The results showed that all the experts had a satisfactory concordance in all the index and there was no need for another round Delphi investigation.The Cronbach's alpha and spit half reliability of the total index system and three first class indexes were all over 0.80;the mean of Spearman correlation coefficients of every third class index with the first class index of the same domain was over 0.51 and the mean of correlation coefficients of every third class index with first class indexes of other domain was equal or less than 0.51,with significant differences (P<0.05).The Kendall W^a coefficient for the data collected in site investigation and Delphi consultation was 0.730 (P<0.030).Conclusion The Early Warning Index System of Major Diseases in Wuhan Metropolitan Area includes cadiovascular diseases,respiratory diseases,and enteric infectious diseases.The reliability and validity of the index system ware satisfactory and the index weight distribution is rational.The index system might be useful in the early warning of major diseases in Wuhan metropolitan area.