The invention provides a gas inflow heating device for an engine. The gas inflow heating device for the engine comprises a temperature sensor used for detecting the temperature in the engine, a heating device arranged between a gas inflow manifold and a cylinder cover gas inflow pipeline and used for heating air entering the cylinder cover gas inflow pipeline from the gas inflow manifold, a waste gas inflow pipeline and an electromagnetic valve, wherein the first gas inflow end portion of the waste gas inflow pipeline is connected with an engine exhaust pipe, and the second gas inflow end portion opposite to the first gas inflow end portion is connected with a gas inlet of the heating device; and the electromagnetic valve is arranged on the first gas inflow end portion, when the temperature in the engine is lower than a first preset temperature, the electromagnetic valve is started, and gas in the engine exhaust pipe enters the heating device through the waste gas inflow pipeline. According to the gas inflow heating device for the engine, under the condition that the engine performance is not affected, the problem that fuel mixed gas is formed because methanol fuel is not prone to atomization in a low temperature environment and the problem that harmful gas emission is caused when combustion of methanol is not complete at low temperature are effectively solved.