The combustion process in a diesel engine, and therefore the emissions characteristics of such an engine, are typically controlled by mixing of fuel and air. To better understand this process, the injection process must be better understood. This paper explores spray characteristics of emulsified diesel blends with water by using a newly constructed constant volume chamber system. The schlieren technique and a high speed video camera are used to record the spray process, and MATLAB software is used to process the spray digital images. Of particular focus is the effect of water magnitude in emulsified fuel, as well as ambient pressure and injection pressure on the spray characteristics. Results show that as the magnitude of water increases, the spray tip penetration increases, but the spray cone angle, spray volume, and spray area decrease. When the ambient pressure is increased, the spray resistance is greater, and the spray tip penetration will be shorter, the spray penetration velocity will be slower, and the spray volume and area will be smaller, but the spray cone angle will be larger. At higher injection pressures, spray tip penetration is increased, penetration velocity increases, and spray area and volume increase, while cone angle decreases.