The work aims to prepare edible gelatin-chitosan composite films based on different concentrations of acetic acid, and explore the effects of acetic acid concentrations (mass fraction) (1%, 1.5%, 2% and 2.5%) on the properties and application of the films. The physical and chemical properties of the edible composite films were analyzed by water vapor permeability, oxygen permeability, mechanical properties, SEM, thermal performance, FTIIR and Raman spectra. And the mechanism was analyzed. It was found that the film prepared with low concentration of acetic acid had low vapor permeability and oxygen permeability, and its tensile strength and elongation at break were relatively higher. The low concentration of acetic acid can improve the surface smoothness and thermal stability of the film. FTIR and Raman tests showed that the interactions among chitosan, gelatin, acetic acid were mainly hydrogen bonding, resulting in the formation of the compact films. It is concluded that gelatin-chitosan film with 1% acetic acid performs better under the comprehensive analysis. The films could be made into packages for food like peanuts. This study will provide some reference for application of gelatin-chitosan composite films in food packaging.