In this study, a new in situ film of compound iodine oral spray was prepared by in situ gel technology, which was used to exert sustained-release effect for promoting the repair of oral ulcer wounds. Firstly, the formulation and process of the spray solution were optimized according to the spray state and film-forming time. The drug-liquid mixing ratio was evaluated by film-forming time and drug film adhesion. The drug content, stability, pH, and spraying effect of compound iodine oral spray prepared by the optimal formulation were investigated; and the physicochemical properties, including film formation time, solubility, hygroscopicity, moisture retention and in vitro release of drug film were evaluated. In addition, the biocompatibility of the film-forming materials and proliferation ability of drug film were investigated by cell experiment. Through the rabbit oral ulcer model, the in vivo film-forming and repair-promoting effects of compound iodine oral spray were evaluated. The results showed that the pH of liquid A and liquid B prepared were 6.21±0.02 and 6.42±0.03, respectively, which were in line with the normal pH range of oral mucosa; liquid A and liquid B had good stability and spray state; the iodine content in solution B was (1.96±0.01) mg/mL; the in situ membrane formation time in vitro and in the oral cavity were (118.3±3.6) s and (133.3±4.6) s, respectively; the 24-hour dissolution rate was (87.31±1.74)%, the moisture absorption rate was (124.17±7.13)%, and the moisture retention rate was (26.85±2.50)%; the iodine content in the oral spray was (47.42±0.39) mg/g, with good flexibility and adhesion, as well as some slow-release effect. In cell experiment, the film-forming materials showed good biocompatibility and growth promotion ability. The results of the rabbit oral ulcer experiment showed that the compound iodine oral spray could rapidly form a film in vivo and significantly promote the repair of oral ulcer. In conclusion, the compound iodine oral spray in situ film with a stable preparation process can effectively promote the repair of oral ulcer wounds, which provides a new idea for the research of novel oral mucosa formulations, with a good prospect of transfer.