The work aims to study the effect of chitosan on microstructure and corrosion resistance of aspartic ac-id-Ti-Zr-based conversion coating on aluminum alloy surface. Aspartic Acid-Ti-Zr-based conversion coating with different contents of chitosan was prepared on the surface of the 5083 marine aluminum alloys. The microstructure and composition of the conversion coating were analyzed by SEM, EDS, FT-IR and XPS. Open-circuit potential-time curves and polarization curves of conversion coatings with different contents of chitosan were analyzed by electrochemical work station. The aspartic ac-id-zirconium-titanium conversion coatings with different contents of chitosan were successfully prepared. The crack of conversion coating was reduced after the addition of chitosan. There were strong hydrogen bonds in the infrared spectrum results, and characteristic peaks corresponding to aspartic acid and chitosan appeared. XPS results showed that Zr in the conversion coating existed as an organic complex of ZrO2 and Zr. Ti in the conversion coating existed in the form of TiO2, and the structure of aspartic acid and the peak position of chitosan existed. The corrosion current density was reduced from 3.966×10-6 A/cm2 to 3.274×10-7 A/cm2. The corrosion resistance was significantly improved. Chitosan can be added to conventional Aspartic Acid-Ti-Zr-based conversion coating to form a complex conversion coating. The appropriate addition of chitosan can improve the cracking and corrosion resistance of the Zr-Ti-based conversion coating. When the amount of chitosan is 15 mL/L, the crack of the conversion coating is the least, and the corrosion resistance of the conversion coating is optimal.