The invention discloses a C20 curing product based on viscous spoil and sand spoil. The C20 curing product based on the viscous spoil and the sand spoil comprises the following raw materials in parts by mass: 13-20 parts of cement, 40-55 parts of the viscous spoil, 8-18 parts of sand spoil, 1-4 parts of gypsum, 8-15 parts of mineral powder, 13-15 parts of water and a proper amount of an enhancer. A preparation of the product comprises the following steps: fully and uniformly mixing the raw material components according to the proportion to obtain a mixed mixture; adding the mixed mixture into a precast mold; classifying for forming under the working pressure being 20MPa so as to obtain formed test pieces; immediately de-molding the formed test pieces; and naturally watering the test pieces after de-molding for maintenance indoors so as to obtain a viscous spoil and sand spoil curing material. The cubic test pieces prepared from the viscous spoil and sand spoil curing material prepared by adopting the method can meet the intensity requirement of C20 concrete, and can replace concrete materials for preparing water conservancy project materials such as slope protection bricks and ballasting blocks. According to the C20 curing product based on the viscous spoil and the sand spoil, and the preparation method of the C20 curing product based on the viscous spoil and the sand spoil, the viscous spoil and the sand spoil in navigation projects are reasonably utilized, sources are saved, and the cost is low.