The oil-immersed distribution transformer has a large number of heat sinks on the surface

which makes the sound field calculation and structure optimization analysis of the oil tank difficult. Therefore

a kind of method for structure modal analysis and sound field calculation considering heat sink is determined in this paper. The equivalent simplified modeling of the heat sink structure is performed by introducing the moment of inertia parameters. The modal analysis results

which are obtained by the simplified model

are used as reference basis and the true modal shape and natural frequency of the transformer are selected from the modal calculation results of the complete transformer model. Moreover

more reliable calculation method of sound field is determined by way of analyzing the influence of such two methods as linear interpolation and modal expansion on the sound field calculation results. The results show that the main modal result of the first three orders adopting inertia moment equivalence is very close to the result obtained by the complete structural model

has good reference and can be used directly for optimization analysis of structure. Moreover

the sound field calculated by linear interpolation method is closer to the actually measured result and can be used for sound field calculation of transformer. The research results can provide support for the optimal design of the oil tank structure of distribution transformer.