The technology of a wall catalytic reforming reaction is introduced to the combustion of emulsified oil. A small quantity of hydrogen generated by a catalytic reforming reaction can effectively overcome disadvantages such as ignition delay and the decrease of power for emulsified fuel. Thus, catalytic combustion of emulsified fuel can save fuel consumption by about 20%. The comparison between computed and measured results shows that the wall catalytic reforming reaction can reduce the ignition delay of emulsified fuel. In addition, the Sauter mean diameter of emulsified fuel with catalytic reforming becomes smaller than that of pure diesel and emulsified fuel without catalytic reforming because of the large coefficient of diffusion and heat conduction for hydrogen, which increase the rate of heat transport to the surface of droplets. Therefore, it can reduce specific fuel consumption far more than that of emulsified fuel without catalytic reforming reaction.