The invention discloses a method for producing phosphorus copolymerized flame-retarding terylene high-strength industrial yarns, which is characterized by comprising the following steps: pumping ethylene glycol (EG) and purified terephthalic acid (PTA) into a pulping kettle according to a molar ratio of 1.15 for pulping; after uniform pulping, transferring the uniform pulp into an esterification kettle for esterification; after the esterification is accomplished, adding blended liquid of a flame retardant, uniformly mixing, and adding the mixture into a polymerization kettle; after the polymerization is accomplished, discharging and cutting to obtain flame-retarding polyester chips with a viscosity of 0.61; feeding the prepared flame-retarding polyester chips into a solid-phase polymerization system, and improving the viscosity to 0.90 to 1.10; and melting at a high temperature into molten spinning solution in a screw extruder, spinning by a spinning component, drawing, and thermally setting to obtain phosphorus copolymerized flame-retarding terylene high-strength industrial yarns. In the invention, a copolymerized flame-retarding modification process is used for flame-retarding modification of the polyester, and the obtained terylene industrial yarns have high strength and a permanent flame-retarding property.