The invention discloses a cemented gravel dam. Impermeable layers are arranged on the upper stream surface and the lower stream surface of a dam body; the impermeable layers are polyurea elastomer impermeable layers obtained by adopting a rotary spraying membrane construction method or other construction methods; and if necessary, polyurea elastomer impermeable layers can be arranged on all water blocking and flow passing surfaces of the dam body. Polyurea is a waterproof, anti-corrosive, impact resistant, wear resistant, slippery resistant and heat resistant material, has the advantages of no VOC (volatile organic compound), environmental protection, fast curing, excellent physicochemical mechanical properties, high construction efficiency and the like, and the impermeable property of the cemented gravel dam can be improved obviously by adopting the polyurea elastomer impermeable layers.