Abstract: This article expatiates the properties of four kinds of high performance engineering plastic - PPS, PEI, PEEK, PES, and discusses whether they can replace PSU which is the material traditionally used to make transformer framework. Through machining property test, solvent resistance test, high-low temperature cycle environmental test and temperature impaction test, it is proved that PSU can be replaced by PPS, PEI, PEEK as the material for manufacturing insulation structure.