The invention discloses a preparation method of 
phosphorus building 
gypsum-based water-resisting and self-leveling 
mortar. The anti-
cracking mortar is prepared from the following components in percentage by 
mass: 50 to 90 percent of 
phosphorus building 
gypsum, 10 to 50 percent of baked sand, 0 to 20 percent of 
cement, 0 to 5 percent of 
fly ash, 0 to 15 percent of an active activator, 0 to 3 percent of a 
water repellent, 0.1 to 1 percent of a high-performance 
plasticizer, 0 to 0.2 percent of an anti-
settling agent, 0 to 0.2 percent of a flocculating agent, 0.01 to 0.4 percent of a 
calcium sulfate retarder, 0 to 3 percent of a high-molecular 
polymer and 0.05 to 0.3 percent of a high-performance defoaming agent. According to the preparation method disclosed by the invention, 
phosphogypsum which is an 
industrial waste is used as a main 
raw material, so that the prepared self-leveling 
mortar is high in 
quality performance and high in 
water resistance, can be applied to a leveling project for indoor and outdoor grounds, is particularly applicable to a floor heating project and a wood floor 
base course leveling project, is high in coagulation and hardening speed, high in volume stability,high in temperature change resistance, and low in cost, and does not crack, and product properties meet relevant standard requirements; a production process is simple and low in 
energy consumption; compared with other self-leveling mortar products, the 
phosphorus building 
gypsum-based water-resisting and self-leveling mortar is higher in market competitiveness and high in practicability.