The emulsifying properties of pea proteins and the molecular mechanism that affected the emulsifying properties were investigated in this study. The pea protein powder was used to prepare emulsions using soy bean oil by homogenizing technique. The parameters of the emulsions were studied including the emulsifying property, stability, interfacial adsorption property and the competitive adsorption of components of pea proteins. The results indicated that when the protein concentration was within 1 to 30 mg/mL, with the increasing of concentration, the particle size of emulsions was decreasing, the emulsifying property and stability improved, and protein aggregates were losing the superiority in competitive adsorption, while the proportion of vicilin and legumin increased. When the protein concentration was higher than 20 mg/mL, the average diameter of oil droplets was lower than 1.06 μm, the interfacial adsorption of pea proteins would reach the saturation state. While there were more vicilin than legumin in surface proteins, whenthe proportion of aggregates was very low, which was less than the initial pea protein composition.