Research on combustion characteristics of diesel, natural gas dual fuel engine, and to analyze the influence of pilot diesel fuel supply system parameters on the combustion characteristics of dual fuel engine. Based on the experiment, firstly comparing the combustion characteristics of diesel engine with diesel, natural gas dual fuel engine, and compared the effect of load on the combustion characteristics of dual fuel engines, and specifically elaborated the load, speed, rate of substitution, effects of ignition oil quantity, inlet concentration of the mixed gas, the fuel supply advance angle and other factors on combustion changes of dual fuel heat release rate, pressure, discharge characteristics. Analysis of the natural gas / diesel dual fuel engine is currently studying the existing problems of key technologies and development prospects.