Abstract: There are a large number of ac filters, reactors and other reactive compensation equipment in the ±800kV converter station. Continuous switching of capacitive and inductive equipment may trigger resonant overvoltage. This article is based on power electronics and electromagnetic transient calculation program established ±800kV ac system for electromagnetic transient model, to start debugging infill transformer and the ac system for filter when possible resonance overvoltage are analyzed in the simulation, and compared with the field measured data validation. The results show that the transient voltage during the start-up and commissioning of ac system of ±800kV converter station is within the national standard limit and no resonant overvoltage is generated.