Considering the complexity of the process of integrated risk evaluation on urban natural disaster

the authors propose a method for risk evaluation based on case-based reasoning.Paying more attention on the uncertainty

it takes the integrated risk as a uncertain system comprising hazard and vulnerability to get the risk values from set pair calculation

which would be considered as forward examples.The variable fuzzy cluster method is used to process the risk results for CBR to get a new sample structure which is good for quick retrieve.Some revised examples become new samples through circulation

and the number and variety will of sample increase.The above process will simplify the risk evaluation and obtain more accurate result.The paper finally verifies the method through an example.