The invention discloses a lamp shade for a water pool wall lamp. The outer surface of a housing of the lamp shade is a composite curved surface consisting of a plurality of concave-convex cambered surfaces with different curvatures and same wall thickness; a first cambered surface, a concave cambered surface and a second cambered surface are formed on the composite curved surface front top to bottom; by taking the horizontal central line of the lamp shade as a symmetry axis, the concave cambered surface in a mode of asymmetry up and down is obliquely arranged downwards, is connected with the upper end edge of the housing to form the first cambered surface, and is connected with the lower end edge of the housing to form the second cambered surface; uniform convex arcs are formed on the composite curved surface in a direction parallel to the horizontal central line of the lamp shade; and when the lamp shade is combined with a lamp body to be arranged in water, water can be utilized as alens to match the concave-convex cambered surfaces on the lamp shade, so that light energy can be fully utilized, the refraction angle of the light is changed, refection and diffuse scattering effects after the light of a light source is emitted are improved, an illumination region is regulated, the illumination area is enlarged and the illuminance in the illuminated region is improved.