Compared to traditional epoxy resin insulation materials, novel ceramic materials demonstrate certain application potential in SF6-insulated HVDC electrical equipment. This paper investigates the DC-temperature field coupling characteristics of ± 800 kV DC wall bushings. It explores the structural design optimization of metal inserts for ceramic support insulators in ± 800 kV DC wall bushings, including: optimized design of bottom metal inserts; optimized design of separated top metal inserts; and optimized design of integrated top metal inserts. Comparative analysis of the combined DC field-temperature electric field characteristics for the overall post structure reveals that the ceramic insulating post exhibits uniform surface electric field distribution with lower magnitude. Simultaneously, the integrated top metal insert design demonstrates superior performance characteristics compared to the separated counterpart.