The invention relates to a sulfur hexafluoride gas phase evaporator which comprises a shell, a heating pipe, heating pieces and a temperature sensor. The heating pipe and the heating pieces are all arranged inside the shell. The heating pieces are distributed on the periphery of the heating pipe in a surrounding mode. The shell comprises an inlet and an outlet. The temperature sensor is arranged in the shell. When the temperature of SF6 around the outlet is not within the threshold value range, the heating pipe performs heating or stops heating so that the temperature of SF6 around the outlet can be within the threshold value range. By arranging the heating pipe and the heating pieces inside the shell of the evaporator, the heating pipe and the heating pieces make sufficient contact with SF6 liquid, the contact area between the SF6 and the heating source is increased, the SF6 liquid is heated more uniformly and sufficiently when the SF6 liquid is heated, the SF6 liquid can be sufficiently heated into SF6 gas, and the phenomenon that electrical equipment is damaged by arcing caused when the SF6 liquid enters the electrical equipment is avoided.