The Separation of oil from the Inner Mongolian oil sand with washing method and its tails treatment for environment protection have been studied. The factors including washing temperature, the reagent weight fraction, the disengaging time and agents sand ratio on oil separation were checked, while in the tails treatment experiment, effect of the weight fraction of reagent on tailings oil content has been studied as well. The experimental results show that best oil separation performance could be obtained under the following conditions: washing temperature 80 ℃, the reagent mass fraction of 8%, separation time of 20 min, sand agent mass ratio of 2∶1. Inner Mongolia tailings treatment by washing multiply with low concentration of reagent, and the mass fraction of the oil content of the tailings can be reduced to 0.3%, which can meet with the requirement of emission standards of the tailings.