A high-strength thermal-stability polyester industrial yarn is prepared by spinning, winding and coordination treatment of a modified polyester after a solid-state polycondensation; wherein the method of coordination treatment comprises: soaking the wound fiber in an aqueous solution of a coordination agent, and the concentration of the aqueous solution of the coordination agent is 0.1-0.2 mol/L; wherein the condition of coordination treatment is 48-72 hours at 80-100° C., and the concentration of the aqueous solution of the coordination agent is 0.1-0.2 mol/L; wherein the polyester segments of the prepared high-strength thermal-stability polyester industrial yarn comprises a terephthalic acid segment, an ethylene glycol segment and a 2,6-pyridinedicarboxylic acid segment, and 2,6-pyridinedicarboxylic acid segments of different polyester segments are coordinated by Fe3+, the molar ratio of the terephthalic acid segment to the 2,6-pyridinedicarboxylic acid segment is 1:(0.03-0.05).