The invention provides a power distribution network abnormal voltage assessment method based on fuzzy evaluation. The method comprises the following steps that S1, active load, reactive load and voltage amplitude of target electric network load nodes are calculated; S2, fuzzy clustering is performed according to the load, and the load value is divided into m typical load modes; S3, the weight of each typical load mode is calculated; S4, a fuzzy evaluation system is established; S5, fuzzy comprehensive evaluation is performed; S6, the comprehensive evaluation result is quantified; and S7, the steps S2 to S 6 are repeated, voltage quality comprehensive evaluation is performed on each node of the power distribution system of a target area and the average value of the evaluation scores of all the nodes is calculated so that voltage quality evaluation of the target electric network can be obtained. The degree of severity and the range of influence of voltage abnormity can be objectively evaluated so that voltage abnormity caused by accidental factors and systemic factors can be effectively discriminated, the causes of abnormity can be analyzed, and thus targeted equipment updating and treatment can be performed.