The invention discloses an expansion valve with a heat insulation function. The expansion valve comprises an expansion valve body. A heat insulation cover arranged outside the expansion valve body in a sleeving mode is arranged on the expansion valve body. A door structure is arranged on the shell wall of the heat insulation cover. By the adoption of the structure, the expansion valve has the following advantages that 1, the influences of thermal radiation of an exhaust device of an engine and a forecabin are isolated; and 2, when the temperature in a gap between the heat insulation cover and the expansion valve body is too high, the door structure on the heat insulation cover can be automatically opened by a system, air convection is achieved between the gap between the heat insulation cover and the expansion valve body and the space outside the door structure, the temperature in the heat insulation cover is lowered in a short period, and then the system controls the door structure to be closed; and if the door structure is opened for too long, the thermal radiation of the exhaust device of the engine and the forecabin cannot be isolated, on the contrary, the heat in the heat insulation cover is increased, and an adverse effect is achieved.