Gas control system and gas control method of off-road gas engine

A gas control system of a non-road gas engine and a gas control method thereof are disclosed by the present disclosure. The gas control system includes a mixer, the mixer is provided with an air inlet, a gas inlet and a mixed gas outlet respectively, the air inlet is provided with a first pressure sensor, the gas inlet is provided with a second pressure sensor and a pressure regulating valve that are spaced apart, and the mixed gas outlet is provided with a third pressure sensor; the first pressure sensor, the second pressure sensor, the pressure regulating valve and the third pressure sensor are respectively electrically connected to a controller, and the controller controls an opening degree of the pressure regulating valve according to pressure information fed back by the first pressure sensor, the second pressure sensor and the third pressure sensor so as to adjust an air-gas ratio of the mixed gas. The system has a simple structure. By disposing a pressure regulating valve at the gas inlet, the pressure of the gas entering the mixer is controlled, and the air-gas ratios required under various working conditions are controlled, which realizes a closed-loop control so that a control range of the air-gas ratio is smaller, the accuracy is higher, and a transient response speed of the engine is improved.