Abstract: Dialdehyde cellulose(DAC) was prepared by the oxidation of celluose with sodium periodate. Then, the condensation reaction of DAC and urushiol was carried out to prepare the cellulose-based urushiol acetal composite coatings. The properties and structure of DAC were characterized by FT-IR, XRD and SEM, while the properties and structure of composite coatings were characterized by FT-IR, TG and SEM. The results showed that DAC was successfully prepared. The properties of the composite coatings changed significantly with the increase of DAC addition. It was found that the composite coating with 20% DAC addition had better comprehensive properties with the surface drying time of 140 min, adhesion(Baige knife method) of 4B, flexibility of 3 mm, glossiness of 26.3%, and the roughness of 2.2 μm. Notably, the acid and salt resistance of the film did not change, but the alkali resistance was improved obviously. The heat stability was improved and the inner structure of the film was denser and more uniform.