The invention belongs to the technical field of dual-fuel engines and relates to a diesel-natural gas dual-fuel system and a control method. The diesel-natural gas dual-fuel system provided herein has a fuel injection pump corresponding to multiple cylinders; an intake master pipe is also provided in correspondence with the multiple cylinders and is communicated with an air pipeline; an air filter, a booster and an intercooler are arranged between the air pipeline and the intake master pipe from front to rear; a boosted air pressure sensor and a boosted air temperature sensor are also arranged between the intercooler and the intake master pipe; the diesel-natural gas dual-fuel system also comprises a fuel gas supply pipeline that is provided with a natural gas pressure sensor and a natural gas temperature sensor which are positioned behind a self-operated differential pressure balance valve; the fuel gas supply pipeline is communicated with multiple fuel injection valves corresponding to the cylinders through the self-operated differential pressure balance valve. The diesel-natural gas dual-fuel system and the control method have the advantages that fuel gas replacement rate and heat efficiency are increased and fuel consumption cost and emission are decreased.