The three-dimensional shear strength reduction method is used to evaluate the stability of an idealized slope stabilized with anchors, where the soil-anchor interaction is simulated by zero-thickness three-dimensional interface elements, and the effects of the direction angle, position, spacing on the slope stability are numerical studied. The results show that the reinforcing mechanisms of anchors in slopes are to increase the shearing resistance on the slip surface,and the failure mechanism, predicted by SSR, agrees well with the critical slip circle given by Bishop’s simplified method. The better stabilizing effects can be obtained when the anchors are installed with a small angle between the anchor and the horizontal direction, and slightly closer to the slope toe.