Gas charging system applied to natural gas engine

The utility model relates to the technical field of engines and in particular relates to a gas charging system applied to a natural gas engine which is manufactured by modifying a diesel engine. The gas charging system comprises a gas cylinder cover, and an air filter, a booster, an intercooler, an electronic throttle valve and a mixer assembly which are sequentially connected with one another by virtue of a pipeline, wherein a main gas charging pipe is arranged inside the gas cylinder cover; the inlet of the main gas charging pipe is arranged on one side of the gas cylinder cover; the mixer assembly is connected with the inlet of the main gas charging pipe by virtue of the pipeline; a natural gas inlet is formed in the mixer assembly; the gas charging system also comprises an anti-surge valve; a gas charging hole of the anti-surge valve is communicated with a pipeline between the booster and the electronic throttle valve; a gas discharging hole of the anti-surge valve is communicated with a pipeline between an air filter and the booster; a reference hole of the anti-surge valve is communicated with the main gas charging pipe. The gas charging system applied to the natural gas engine is simple in manufacture process, low in cost, easy to maintain and low in fault rate.