The invention provides a dual-fuel unitized engine, a fuel oil control method and a power device. The method includes the steps of detecting the rotation speed of the engine, the temperature of engine oil, the temperature of cooling water of the engine and the opening amount of an accelerator pedal, judging the operation state of the dual-fuel unitized engine according to the detection value, determining the jet amount of fuel oil according to the operation state of the dual-fuel unitized engine, and controlling the opening amounts of a first electromagnetic valve and a second electromagnetic valve according to the jet amount of the fuel oil. By means of the fuel oil control method and device for the dual-fuel unitized engine, the problem that a traditional single-fuel pre-mixing compression ignition burning mode is narrow in application load work condition range is solved, and the problems that an 'air inlet passage+direct injection' dual-fuel system is complex in structure and high in control difficulty are solved, real-time regulation of the fuel mixing proportion is completed before oil jetting through a dual-fuel oil sprayer, and a novel engine fuel burning control strategy is provided.