The invention relates to a surface protecting block of a mound breakwater. The surface protecting block comprises a base body (A), and is characterized in that the base body (A) is provided with a base plate (1) and an arching protecting body (2), the protecting body (2) is arranged on the upstream face of the base plate (1), a cavity with an open end is formed between the protecting body (2) and the upstream face of the base plate (1), and a plurality of drainage holes (21) are formed in the surface of the protecting body (2). According to the arching protecting body mainly playing a role in water retaining, wave force can be attenuated better due to the shape of the arching protecting body; besides, since the cavity is formed between the protecting body and the base plate, a water body can fall when waves impact the protecting body, rotational flow is formed in the cavity, and therefore the acting force of water flow is further reduced; in addition, since the drainage holes are punched in the protecting body, on the one hand, water in the cavity can be drained through the drainage holes, one the other hand, convection can be generated between the drained water flow and waves of a next time of wave impact, so that the wave force is reduced, and damage power of the waves to the surface protecting block is reduced.