The emulsification technology was applied to prepare two-phase W/O and three-phase O/W/O biodiesel emulsions. The effects of emulsifier dosage, temperature, HLB value on the emulsion stability, fuel properties of emulsion and emission were investigated by experiment. The experimental results showed that emulsifier dosage 0.5%, temperature 30℃ and surfactant mixture when aHLB＝13 produced the highest emulsification stability, while aHLB＝6 produced the lowest stability and the most significant extent of water-oil separation among the various HLB values for O/W/O emulsion. In addition, it was found that the W/O emulsion had a smaller mean droplet size and lower volumetric fraction of the dispersed phase than those of O/W/O emulsion respectively, and the heating value is higher than that of O/W/O emulsion and neat biodiesel if water content was deducted from the calculation of the heating value. The brake specific fuel consumption of emulsions was higher than that of neat biodiesel and diesel. CO emissions of emulsions were higher than those of neat biodiesel, but were lower than those of diesel. NOx emissions of emulsions were lower than those of biodiesel and diesel.