V/UiO-66 catalyst and modified Sn-V/UiO-66 catalyst were prepared by impregnation method with UiO-66 as carrier, and their potassium poisoning was simulated. The reaction and deactivation mechanisms of vanadium-titanium catalyst were analyzed. Results demonstrate that the crystallographic form of catalysts barely changes after K-loading, and the specific surface area of the catalysts has an irregular fluctuation. The catalyst activity is decreased rapidly after the alkali metal was loaded due to the degraded metal redox performance and the rapidly decreased surface acid content of the catalysts. The addition of Sn can enhance the interaction between VO_x and other components, which thereby increases the V⁵⁺ content and reducibility of VO_x. Thus, VO_x on the surface of Sn-V/UiO-66 catalysts can provide more acid sites. The poisoned K-Sn-V/UiO-66 catalyst still has high total acid content and strong redox property, presenting the high resistance of Sn-V/UiO-66 catalyst against alkali metal poisoning.