The major factors affecting the viscosity of the crude oil from Jilin oilfield were figured out by using modern physical analysis technology. A type water soluble viscosity reducer was selected, and the emulsification method was used. By the static performance evaluation experiments, the emulsion stability, particle size distribution, interfacial tension, viscosity reduction rate and washing oil efficiency were studied and the viscosity reducing effect of A type water soluble viscosity reducer was evaluated. The results indicated that wax content of Jilin crude oil was up to 14.7%, which was the major factor affecting the viscosity. The higher the concentration of the reducer was, the smaller the water separation was; the sharper the size distribution of the emulsion, the lower the interfacial tension was and the more stable the emulsion was. The water separation of oil emulsion decreased with the increase of the concentration of the reducer; moreover, the trend was notable with the higher oil-water ratio. The viscosity reduction rate of the crude oil increased with creasing the concentration of the reducer and lowering oil water ratio, and which could reach up to 91.5%. Besides, the reducer had a good washing oil efficiency of 61.1%.