The polyester glycol was synthesized by copolycondensation, and the hydroxyl and acid value were determined by the chemical analysis method. Through the secondary chain extender, the ester-soluble polyurethane was obtained, with them the red ink was prepared, the relationship between adhesion of ink on the BOPP and polyurethane addition was studied. The infrared spectrometry was carried on the qualitative attribute to the polyester glycol and the polyurethane, and the responsiveness of isocyanate with the variation of reaction time has been studied.