The invention discloses spray gypsum for 3D printing. The spray gypsum is prepared from the following raw materials in parts by weight: 40-70 parts of gypsum, 30-50 parts of sand, 5-15 parts of talc powder, 0.2-0.3 part of cellulose, 3-6 parts of activator, 3-5 parts of water reducing agent, 0.04-0.06 part of starch ether, 1-3 parts of rubber powder, 1-3 parts of wood fiber and 0.1-1 part of waterproof agent. According to the spray gypsum disclosed by the invention, by adopting the industrial waste desulfurized gypsum, overall manufacturing cost is lowered, and the spray gypsum is environment-friendly; by adopting the activator to stimulate activity, a firing-free purpose is achieved, the spray gypsum can be quickly formed, and the printing efficiency and the printing precision are improved; since the water reducing agent cooperates with the waterproof agent, a waterproof film can be formed outside, the film is denser, and the waterproof property is higher.