The valve-side bushing of converter transformer bears AC-DC compound voltage, which has strict requirements on the performance and quality of the bushing. Under DC voltage, the accumulation of space charge at the interface of different medium causes the distortion of local electric field, and the existence of metal particles greatly increases the local electric field strength, both of which reduce the insulation performance of the bushing. In this paper, according to the structure of valve-side bushing of converter transformer, the simulation model of valve-side bushing is established by using finite element analysis software. The electric field distribution of the bushing under different types of voltage after adding space charge and the influence of metal particles on the local electric field are analyzed. The results show that the space charge at the dielectric interface is easier to accumulate under DC voltage, and the space charge is able to cause the distortion of the local electric field inside the bushing under AC-DC compound voltage. The degree of local electric field distortion of metal particles under DC voltage is greater than that under AC voltage, and the influence of metal particles on the degree of electric field distortion has little to do with its location in SF₆.