Abstract: To determine the landslide stage for suitable application of the point safety factor method, calculational results obtained using this method and the rigid-body limit equilibrium method were analyzed and compared, and factors influencing point safety factor were analyzed. The results show that the beginning stage of the plastic flow state of sliding zone is suitable to the use of point safety factor, so the applicable condition of the point safety factor method is the critical state of sliding beginning. At the stage, in a two-dimension condition the whole safety factor based on the point safety factor method shows a good agreement with that based on the rigid-body limit equilibrium method; in a three-dimension condition, the calculated results are accorded with the reserving strength concept, i.e., the safety factor of sliding decreases K times when its shear strength decreases K times.