Based on the fact that risk assessment of environmental pollution accidents among factories is a multi-criteria and multi-stage process, and is of relativity and fuzziness, the fuzzy rank theory is developed and applied to solve such ranking problems by means of the fuzzy weighted distance, membership degree and the extensive Minimum Square Criterion. Furthermore, the methodology is applied to assess the risk of potential pollution accidents among four important chemical factories in Dalian, and the results are more reasonable than those obtained by the Index Method.