The invention belongs to the technical field of building materials, and in particular relates to a phosphorus slag powder doped dry powdered anti-crack mortar. The phosphorus slag powder doped dry powdered anti-crack mortar is prepared from ordinary Portland cement, river sand, phosphorus slag powder, slag powder, slag powder activity excitant, cellulose ether, polypropylene fiber, wood fiber, modified attapulgite, a defoaming agent and a water reducing agent. In the invention, the average particle size of the phosphorus slag powder is 30-40 nu m, the specific surface area measured by nitrogen adsorption is 350-400 m<2>/kg, and the mass coefficient K is 1.3-1.4, therefore, the anti-crack mortar has a certain potential volcanic ash activity; the dry powdered anti-crack mortar disclosed by the invention is convenient to operate and easy to control, can be used just after being added with water and stirred on the scene, and has the characteristics of good fluidity, good water retention, high bonding strength, good waterproof and water impermeable effects, strong crack resistance, and the like. A product of the anti-crack mortar disclosed by the invention both can be applied to the bonding and plastering of polystyrene foam boards for external wall insulation and extruded sheets, and also can be applied to occasions such as the repair of easily cracked parts, the refurbishment of ceramic tiles for old walls, and the like. According to the invention, phosphorus slag powder can be effectively used, the added value of phosphorus slag powder can be improved, and social and environmental benefits can be improved; the production cost of the anti-crack mortar can be lowered, and the economic benefit can be improved.