Modified polyesters (TTBA-10C, -20C, -30C) that contain phosphorus and chlorine were synthesized by the condensation polymerization of tetramethylene bis(orthophosphate), neohexanediol trichlorobenzoate, 1,4-butanediol and adipic acid, in which tetramethylene bis(orthophosphate) and neohexanediol trichlorobenzoate were prepared previously in our laboratory. In this study, two-component flame-retardant polyurethane coatings (TTBA-10C/HDI-trimer=TTHD-10C, TTBA-20C/ HDI-trimer= TTHD-20C, TTBA-30C/HDI-trimer= TTHD-30C) were obtained by curing at room temperature with the synthesized TTBAs and hexamethylene diisocyanate (HDI)-trimer as a curing agent. The obtained TTHDs were made into coating samples and used as test samples for various physical properties. The physical properties of the flame-retardant coatings containing chlorine and phosphorus groups were generally inferior to those containing only phosphorus group. Flame retardancy was tested by vertical and horizontal combustion method, and $45_{circ}$ Meckel burner method. Since the retardancy of flame-retardant coatings containing chlorine and phosphorus groups was better than that containing only phosphorus group, it could be concluded that the retardancy by the synergism effect of chlorine and phosphorus groups exhibited.