The organic acid solvent system is very significant for the film-forming properties of chitosan. The work aims to explore its potential molecular mechanism to provide a theoretical reference for the related research of chitosan films.The chemical composition and film-forming mechanism of chitosan, as well as the mechanical properties, swelling property, oxygen permeability and water vapor permeability of chitosan films were reviewed in different organic acid solvent systems.Theorganic acid solvent system can provide more protons for the dissolution of chitosan and realize the solubility of chitosan in water. In addition, the number of carboxylic acids and hydroxyl groups in the molecular structure of organic acids, the length of carbon chain, the hydrogen bond and ionic force between organic acids and chitosan were different, which can greatly affect the film-forming performance of chitosan. Theorganic acid solvent system has a crucial effect on the performance of chitosan film, which helps to enhance its applicability in improvement of food quality and preservation.