The invention provides a sand mold printing device and method and belongs to the technical field of 3D printing. The sand mold printing device comprises a base, a forming box trolley, a blanking bracket, a selective laying mechanism, a blanking mechanism, a forming material feeding hopper, an auxiliary forming material feeding hopper, a forming material conveying mechanism, an auxiliary forming material conveying mechanism and a control unit; wherein the base is provided with a guide rail; a printing platform is movably arranged in the forming box trolley which is movably connected with the guide rail; the blanking bracket is erected above the guide rail and fixedly connected with the base; the selective laying mechanism and the blanking mechanism are sequentially fixed to the blanking bracket from bottom to up; the forming material feeding hopper and the auxiliary forming material feeding hopper are arranged on the blanking mechanism in an alternated mode; and the forming material conveying mechanism and the auxiliary forming material conveying mechanism are connected with the forming material feeding hopper and the auxiliary forming material feeding hopper correspondingly. According to the sand mold printing device and method, a linear forming mode is adopted, forming materials and auxiliary forming materials are selectively laid, 3D printing of a sand mold is achieved, and thus the forming speed can be increased.