In order to solve the problem that Ti6Al4V (TC4) alloy is prone to bacterial infection and release of harmful ions as an orthopedic hard tissue implant during long-term service in the human body, a sol-gel method was used to prepare nano-zinc oxide (ZnO) sol with gradient dynamic heating treatment, then the nano-ZnO coating and ZnO/PDA (polydopamine)composite coating were successfully formed on the surface of TC4. The phase structure, micro morphology, coating adhesion, wettability and corrosion performance of the two coatings in simulated body fluids were systematically analyzed. The result shows that the ZnO/PDA composite coating prepared on the TC4 substrate has a more uniform distribution of nano-ZnO particles than that of a single ZnO coating. The chelating effect of PDA on metal ions promotes the bonding force between the substrate and ZnO through the Ti-O-Zn bond. Simultaneously, the introduction of PDA further improves the wettability of the ZnO coating, reduces its surface roughness, and improves the corrosion resistance of TC4.