In order to solve the problems of intermediate frequency(IF) distortion and acoustic performance deficiencies during the use of polymer polyester sound film, a novel laser modification technology on polymer sound film was proposed to improve the function and characteristics of sound film in sound device. Continuous semiconductor laser with the fixed-wavelength of 975 nm was applied to irradiate the surface of sound film with different laser power. Based on the assurance of the sound film surface integrity, different effects of laser irradiation on modification of sound film were obtained. The results show that after laser irradiation, the surface of sound film is intact without breakage or deformation. The surface roughness of the sample decreases, which is benefit for raising the consistency and uniformity of sound film during the vibration process. The sound film distortion, the resonant frequency and other acoustic properties are improved, moreover, the sound quality of the product is significantly improved. Results obtained in the experiment are of great significance to quickly and efficiently enhance the market competitiveness of the sound devices using polymer polyester sound film.