In order to improve the adhesion between titanium alloy TC4 substrate and coating,the effect of different pretreatment methods on the bonding strength of titanium alloy paint layer was researched,found the best way to improve the painting adhesion of titanium alloy parts:adding sand blowing process before passivation;apply AC-131CB sol-gel after passivation;surface modifiers SP1050 are used after passivation.The problem of poor adhesion of paint layer after passivation of titanium alloy parts,which affects the appearance and quality of products,has been solved,and the overall corrosion protection performance of aircraft has been improved.