The work aims to prepare the polyester type polyurethane (PU) films with 1,6-hexamethylene diisocyanate (HDI), polyhexanedioic acid-1,4-butanediol ester (PBA) and diethylene glycol (DEG) as raw materials, and study the in-fluence of ratio (R value) of isocyanate to hydroxy radical on the properties of films. PU was synthesized by prepolymer method. The quality of raw materials required for the reaction was determined by different R values. The films were obtained through solution casting by dissolving the PU in DMF, and then characterized by infrared spectroscopy. The mechanical properties, oxygen permeability, thermodynamic properties, light transmittance and hydrophobicity of films were tested. The films had good mechanical properties. The elongation at break decreased with the increased of R value, while the tensile strength increased first and then decreased. The light transmittance and barrier property decreased with the increased of R value. The hydrophobicity increased with the increased of R value. The feasibility of synthesizing PU with HDI and PBA is proved, and the change of R values has a great influence on the properties of PU films.