The invention discloses a health index based power transformer evaluation method. The method includes the following steps: establishing a quantization index system of a power transformer; acquiring historical status data and current status data of the power transformer, including basic information, routine test data and operation and maintenance data of the power transformer; adopting a statistical tool to perform normalization processing on acquired data and test data, and retaining abnormal values produced due to transformer faults; determining relevance of all variables in the acquired data through a common coefficient analysis method; acquiring contribution values of evaluation indexes when the general health status of the transformer is evaluated through a common factor relevance analysis method; building a transformer health index evaluation module, calculating transformer health indexes, and evaluating the general health status of the transformer according to the health indexes. With the method, the general health status of the transformer can be evaluated comprehensively.