The invention discloses a production process of a tripolymer curing agent high molecular material. The production process comprises the following steps: mixing toluene diisocyanate, ethyl acetate and methylpropanediol; heating the mixture to 60 DEG C to 65 DEG C to react; cooling and adding a catalyst to react for 50min to 60min; raising the temperature to 55 DEG C to 60 DEG C and keeping constant temperature for 1h to 1.5h; when the viscosity is 13''50 to 14''50, detecting different gradient viscosities and adding ethyl acetate according to different gradient viscosity points; when detecting that the viscosity reaches 32''40 to 32''90, cooling to be 45 DEG C or lower than 45 DEG C; when detecting that the viscosity reaches 48'' to 52'', adding an antioxidant and a termination agent; when the temperature is reduced to be 38 DEG C or lower than 38 DEG C, stirring for 30min to 45min to prepare a polyurethane tripolymer. With the adoption of the production process disclosed by the invention, the production efficiency is improved, and the glossiness and the tolerance of the obtained final product are greatly improved, so that the problem that the quality of paint and coating in current markets is common is solved.