The invention discloses a transformer importance degree dividing method. The method comprises steps: the transformer importance degree serves as a target layer, the body feature, the load condition and the external environment information of a transformer serve as a criterion layer, data indexes characterizing the criterion layer are further divided into index layers, and a transformer importance degree hierarchy model is built; real-time data information of index layers of different transformers at the same time is acquired; the acquired real-time data information is subjected to normalization processing; a weight value is assigned to data in each index layer respectively; and according to the normalization result and the weight value of the data in each index layer, the importance degree of each transformer is calculated. The transformer importance degree dividing method has the beneficial effects that the method can integrate multiple sources of information to comprehensively evaluate the current operation condition of the transformer, difference among different types of transformers can be avoided, the method can be used for evaluating the importance degrees of transformers in different environments and with different types, and effective objective basis can be provided for maintenance and replacement of the transformer.