Oil-paper capacitive bushings are widely used in the outlet device of power transformers to connect the transformer and the external electrical network and play the role of insulation and support. It must meet the requirements of electricity, heat, magnetism, and machinery during operation. Its insulation status is related to the power grid. Operational reliability. In this paper, based on the actual failure causes of the casing, four typical defect models of the casing are prepared, and the partial discharge experiment platform of the casing is built. The partial discharge signal of each model is collected based on the pulse current method, and the partial discharge PRPD spectrum and four two-dimensional Spectrogram, study the partial discharge characteristics of the bushing under AC voltage, obtain the partial discharge data of the typical defects of the bushing through experimental research, and study the discharge characteristics, in order to improve the condition moni-toring and operation and maintenance efficiency of the bushing.