More and more high ignition point oil transfor-mers which are fireproofing are applied in many fields. As physical properties of high ignition point oil are different from transformer oil and the value of high ignition point oil viscosity is bigger than the value of transformer oil viscosity, the calcula-tion method of transformer temperature rise used at present is not suitable for high ignition point oil transformer. In this paper a calculation method, which has been verified by experiment results, is pre...