The work aims to prepare microencapsulatedred phosphorus flame retardant wood-plastic composites and study the effects ofmicroencapsulatedred phosphorus content on mechanical properties, heat resistance and flame retardant properties of wood-plastic composites, and expand their range of application. Microencapsulated red phosphorus was used as flame retardant, and was added to the ternary system of low density polyethylene, linear low density polyethylene and wood powder. The flame retardant samples were prepared through secondary extrusion granulation and injection molding. The mechanical properties, heat resistance and stress failure behavior of the material were researched to determine the flame retardant level of materials. Compared with wood-plastic materials without microencapsulated red phosphorus, when the microencapsulated red phosphorus content (mass fraction) reached 10%, the impact strength of the materials increased from 17.4 kJ/m2 to 19.0 kJ/m2; the tensile strength increased from 19.53 MPa to 21.7 MPa; the elongation at break increased by 58.7%; the initial decomposition temperature increased by 73.17 ℃; the flame retardant reached V-0; and the oxygen index reached 28.7%.With the increase of microencapsulatedred phosphorus content, the impact strength, tensile strength and elongation at break of wood-plastic composites all increase; the initial decomposition temperature rises;and the flame retardant and heat resistance becomesbetter. The flame retardant of the material has low additive quantity and good comprehensive performance. It is widely used in packaging, construction, furniture and other fields.