Abstract: The novel soluble polyester-urethane-imide block copolymers containing carboxyl structure were synthesized successfully by four steps of synthesis reaction. Phthalic carboxyl monoester diols(PCMD) were synthesized by the high-pressure solvent-heat reaction of 1,1,1-trimethylolpropane(TMP) with phthalic anhydride(PA) at a molar ratio of 1:1. Then the hydroxyl-terminated polyester with phthalic carboxyl(M_n ca. 2 192) was prepared by the condensation reaction of monomer PCMD and hexanedioic acid at a molar ratio of 6:5. The NCO-terminated polyurethane prepolymers were formed from the reaction of polyester diols with phthalic carboxyl and tolylene-2, 4-Diisocyanate(TDI) or with methylenedi-p-phenyl diisocyanate(MDI) at a molar ratio of 1:2, respectively. Finally, the soluble polyuethane-imide block copolymers were synthesized by the chain extending reaction and imidization of the PU prepolymer with 1,2,4,5-benzenetetracarboxylic dianhydride(PMDA) at a molar ratio of 1:1 and 60℃ for 48 h. The reaction processes were controlled by titration analysis and traced by FT-IR. The in-process products and the polyester-urethane-imide block copolymers were characterized by ¹H NMR and FTIR. The solubility of the products was tested.