The invention belongs to the technical field of transformer state evaluation, and particularly relates to a transformer operation state evaluation method based on PMU data, which comprises the following steps: calculating four indexes capable of reflecting the operation state of a transformer through electric quantity obtained through the PMU data of an electric power system, and evaluating the operation state of the transformer through fuzzy comprehensive evaluation. The method comprises the following steps: acquiring electrical quantity data from PMU nodes arranged on a power transformer, and preprocessing the acquired data; based on the electrical quantity data, state indexes are obtained through calculation, identification and parameter combination; establishing a transformer operationstate evaluation system according to the relationship between the state index and the physical performance; performing comprehensive operation state evaluation of the transformer on the evaluation index by using a fuzzy comprehensive evaluation method; determining a comprehensive grade; and respectively providing a maintenance strategy according to the transformer operation state obtained by thecomprehensive evaluation. The invention has very high engineering application value, is suitable for power systems of different regions and different scales, and has relatively good economy and application prospects.