The combustion characteristics and emission characteristics of the commonly used alternative fuels in the fuel process are reviewed, the three types of alternative fuels are: Alcohols alternative fuel, biological alternative fuel and gas alternative fuel. The three alternative fuels have their own advantages and disadvantages in combustion characteristics and emission characteristics. The dual fuel blended with alcohols has a higher burning rate than pure diesel or gasoline, and emits fewer soot particles. When biofuel is blended into traditional fuel, the thermal efficiency is improved, and the particle diameter of the emitted particles is smaller than that of pure diesel. The use of hydrogen fuel increases the power of the engine, and significantly reduces the content of CO and CO2 in the emissions. With the increase of the proportion of hydrogen, the amount of soot emitted becomes less, but the amount of nitrogen oxide emissions increases. Each of the three types of alternative fuels has its own characteristics and advantages.