Abstract: This paper takes the rubber-impregnated paper bushing on the valve side of the ±800 kV converter transformer as the research object, establishes an electrothermal field coupling simulation model, and explores the influence laws of internal cracks and metal particle infiltration defect parameters on the electric field distortion and temperature field distribution of the bushing. The results show that the field strength distortion of the 4 mm high crack reaches 16.5 kV/mm. The increase of the crack width alleviates the electric field distortion but aggravates the abnormal temperature gradient. The electric field distortion effect of metal particles is closely related to their position and radius. The smaller the radius of the particles near the inner capacitive screen and the radial proximal plate, the more significant the distortion is, and the regional temperature shows a constant distribution.