[Objective] The effects of different shrub planting patterns on slope stability with different slope degrees under rainstorm condition were studied to explore the critical slope degrees for shrubs to stabilize slopes, and to provide a scientific basis for scientific biological engineering to manage mountain disasters. [Methods] Indoor rainfall experiments were carried out by making shrub models to explore the impact of four shrub planting modes (sparse planting, moderate planting, dense planting, bare slope) on slope stability on slopes with different slope degrees (20°, 35°, 50°, 60°). The slope safety factor (F_s) was calculated by using a correction formula considering the influence of shrub weight and root traction. [Results] ① Gully erosion occurred on shrub slopes at 20° and 35°, which was independent of the planting mode; On bare slopes, 50° shrub slopes, and 60° sparsely and densely planted shrub slopes, the damage occurred progressively; Overall slipping failure occurred on moderately planted shrub slopes of 60°. ② Planting shrubs on gentle slopes of 20° and 35° could effectively enhance the stability of the slope during rainfall and reduce the amount of collapse by 4% to 70%; Planting shrubs on steep slopes of 50° and 60° could not only decrease the stability of the slope, but also increase the amount of collapse by 10% to 33%. [Conclusion] Slope stabilization by shrubs can not be simply attributed to effective or ineffective, it is closely related to the slope gradient, so attention should be paid to the choice of planting methods on different slopes.