Aiming at the problem of sliding instability along slope surface during rainfall for 3D mesh flexible protection structure with reinforcement and anchorage, a stability analysis model of slope protection structure under rainfall condition was established based on limit equilibrium theory, considering the splash of rainwater and the scouring effect of flow on the slope surface. Case study was performed and the effects of slope inclination, rainfall intensity, protective layer thickness, distance between anchors and anchorage length on the stability were discussed. The results show that under rainfall conditions, the sliding force of the slope protective structure increases, the anti-sliding force decreases, and the stability of the protective structure decreases obviously. Under the same design parameters for the protective structure, the stability of protective structure decreases with the increase of slope inclination. When runoff forms on the slope surface, the influence of rainfall intensity is relatively small. Under the same slope condition, the stability coefficient of the protective structure decreases with the increase of the distance between anchors and the thickness of the structural layer, and increases with the increase of anchorage length. The distance between anchors and anchorage length have the most significant influence on the stability of protective structure. The distance between anchors should be reasonably determined by the stability analysis model proposed in this paper, and the anchorage length should not be less than 0. 5 m.