The invention discloses a condition evaluation method of a distribution network transformer based on a fuzzy theory. The method comprises the following steps that a three-level index system of condition evaluation of a distribution transformer is established in accordance with data of daily check, routine tests and diagnostic tests of the distribution network transformer, an evaluation index set and a comment set are determined, wherein the evaluation index set contains all indexes in the three-level index system, and the evaluation set contains four conditions of normality, caution, abnormity and severity; an improved analytic hierarchy process is adopted to determine the weight of each index in the evaluation index set; a relatively deteriorative concept is adopted to determine an evaluation matrix of the distribution network transformer; and a grey relation theory is adopted to determine the condition level of the transformer. The condition evaluation method has the following beneficial effects that the condition of the distribution network transformer can be evaluated in batches, losses of manpower and material resources are reduced, the working efficiency and the condition evaluation accuracy are greatly increased, and the condition evaluation method has the advantage of strong practicability.