The invention belongs to the technical fields of mine safety construction, environmental treatment and water and soil conservation, and particularly relates to a method for control over slope instability and water and soil loss of a dump in a northern opencast coal mine. The method includes the following steps that (1) the detailed terrain, hydrologic nets and catchment areas of a top platform anda slope of the dump where disposal is completed are obtained; (2) rainfall data of the region where the dump is located is calculated, and the potential water storage/water holding capacity of the catchment areas and the area of a micro-drainage basin where the catchment areas are located are calculated; (3) water storage plant ponds are distributed in the catchment areas in the top platform of the dump, water holding subsurface wetlands are distributed in the catchment areas on the periphery of the top platform of the dump and in the catchment areas on a slope platform, and the water storageplant ponds communicate with the water holding subsurface wetlands through water guide plant ditches; and (4) suitable plants are planted in the water storage plant ponds, the water holding subsurface wetlands and the water guide plant ditches respectively to conserve water and soil, prevent runoff scouring and improve the landscape effect.