In order to improve the flame retardancy of wood plywood, the intumescent flame retardant coating (IFRC) was prepared by using APP-PER-urea as the basic formula of the system and pyrophyllite as the modified additive. The flame retardancy, hydrophobic and mechanical properties of samples were characterized by means of cone calorimeter, static contact angle machine, scanning electron microscopy, X-ray diffractometer and tensile machine, and the influence of pyrophyllite content on the coating was studied. The results show that adding suitable amount of pyrophyllite in intumescent flame retardant coatings improves the flame retardant effect of coatings. The fire growth index (FGI) reduces by 47%, the fire performance index (FPI) increases by 89%, and the flame retardant index (FRI) increases to 2.5 times when the mass fraction of pyrophyllite powder is 2%. The addition of pyrophyllite powder promotes the formation of continuous and dense carbon layer structure during combustion， produces a molten substance which can effectively isolate oxygen and heat entering the base material and further enhances the flame retardant and thermal insulation properties of the coating. When the mass fraction of pyrophyllite is 2%, the hydrophobic properties of the coating and mechanical properties of wood-made plywood after combustion are the best, and the water contact angle increases by 8°, the tensile strength increases by 45%, and the elongation at break also increases to 8.5 times. The research results can be used as reference for the development of intumescent flame retardant coatings for the wood plywood.