The invention discloses a transformer reliability evaluation method based on an integral health index, and belongs to the technical field of transformer reliability evaluation. The method comprises the following steps that: feature quantities and feature factors of transformer states are selected, and an expression between the feature factors and the feature factors is determined; a weight of each feature factor is determined, the weights are multiplied by values of the corresponding feature factors, and a health index is obtained; a correction coefficient rule is used for correcting the obtained health index to obtain the corrected integral health index; the expected service life of a transformer is determined; the expected service life is used for calculating an aging coefficient of the transformer according to the integral health index value when the transformer is put into operation or quilts the operation; the aging coefficient is used for calculating a time-variation expression of the integral health index of the transformer; and the integral health index is used for obtaining a time-variation expression of the fault rate of the transformer, so that the fault rate is obtained. The method has the advantages that the internal conditions such as main insulation of the transformer and external conditions such as overhaul and operation of the transformer are sufficiently considered during the transformer reliability evaluation, and the transformer reliability can be more precisely and efficiently evaluated.