The insulation problem of Ultra High Voltage Direct Current (UHVDC) wall bushing is the research focus of UHVDC transmission technology. In actual working conditions

the wall bushing is often at ambient temperatures above room temperature due to the influence of internal and external environment

which causes the insulation performance to be affected to a certain extent. For studying the variation of flashover voltage of epoxy resin under AC and DC voltage and the mechanism of temperature influence

an epoxy resin flashover test platform is set up to measure flashover voltage of the epoxy resin under different temperature within the constant SF

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gas pressure

and the reason of flashover voltage variation is analyzed by simulation. The results show that the flashover voltage of epoxy resin first decreases slightly and then increases with the increase of temperature in the range of 25 ℃ to 70 ℃. It shows that there is a minimum flashover voltage in this temperature range. This phenomenon is caused by the joint action of the electric field distribution at the gas-solid interface

the critical electric field strength of SF

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gas and the energy level of surface-trap of epoxy resin. The study results can provide experimental basis for optimizing the insulation configuration of UHVDC wall bushing.