The invention relates to a preparation method of cotton insole deodorization finishing liquid and application. The preparation method is characterized by comprising the following steps: firstly preparing a dispersion agent; grinding AgO, ZnO and TiO2 powder into nanometer grade particles; then, dissolving the nanometer grade particles into the prepared dispersion agent; preparing a nanometer oxideparticle water dispersion body; performing polymerization on acrylic acid, allyl glycidyl ether and dimethyl diallyl ammonium chloride with initiators to prepare polycarboxylates; mixing nanometer oxide particle water dispersion bodies and the polycarboxylates to obtain finishing liquid. The finishing liquid is used for finishing a cotton insole, and the prepared cotton insole is obtained. The prepared finished cotton insole has strong antibacterial performance against staphylococcus aureus, colibacillus and candida albicans; the bacteriostasis rate respectively reaches 99 percent, 97 percentand 97 percent or higher; after 20 times of washing, the strong antibacterial performance is still shown against staphylococcus aureus, colibacillus and candida albicans; the bacteriostasis rate reaches 94 percent or higher; the finished cotton insole has no odor in the whole test process. The preparation process of the cotton insole deodorization finishing liquid is simple; the application is convenient; the popularization is convenient.