根据工厂重大环境污染事故风险评价呈多指标多层次结构，且风险性排序具有相对性和模糊性的特点，运用模糊集理论中的权距离和隶属度概念，并将最小二乘法加以拓展，提出能够有效解决此类多指标多层次排序或优选问题的模糊排序方法。用于对大连市4家重点工厂的事故风险性进行评价和排序，评价结果合理、准确。

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.