The invention discloses a fuel-supply control device of a dual-fuel engine. The fuel-supply control device comprises an accelerator pedal, a fuel transfer switch, a high-pressure gas cylinder, a high-pressure electromagnetic valve, a reducing valve, a low-pressure electromagnetic valve, an accelerator controller, a fuel gas controller and the engine, wherein the accelerator controller comprises an input belt wheel, an input shaft, an output belt wheel, an output shaft, a front gear of the input shaft, a rear gear of the input shaft, a front gear of the output shaft, a rear gear of the output shaft, a front electromagnetic clutch and a rear electromagnetic clutch. The fuel-supply control device has the advantages of realizing the fuel supply changes along with the change of opening degree of the accelerator, maintaining the doping combustion ratio of diesel oil to gas fuel near an ideal value, realizing the transfer between the pure diesel oil combustion and doping combustion and improving the fuel economy of a diesel, along with simple structure, safety and reliability.