Yumen oil sands were chosen as the experimental material to separate bitumen from oil sands through wet-grinding by light oil and washing treatment by washing agent. The tailing sands were characterized by XRD. The factors including amount of light oil, amount of washing agent, concentration of washing agent, and reaction temperature were studied. The results showed that under the reaction conditions of mass ratio of naphtha to oil sands 0.15, mass ratio of washing agent to oil sands 1.5, concentration of washing agent 8%, and reaction temperature 80 degrees C, the oil recovery could be up to 96.5%.