A novel supramolecular inclusion complex was prepared with cationic beta-cyclodextrin and organic phosphoric acid. The indusion action was investigated by UV-vis spectroscopy, and the cationic beta-cyclodextrin inclusion complex was structurally evidenced by H-1 and P-31 NMR and FT-JR. With linear expansion tests, it was found that the novel inclusion complex possessed excellent day stability. FT-IR, single-factor, and response surface method analyses showed that the inclusion complex acid system could not only retard acid rock reaction but also intelligently regulate the acid rock reaction rate to ensure a sufficient amount of acid to react with high-temperature oil-bearing sandstone reservoir in the progress of acid stimulation. On the basis of the core flood tests, an interaction mechanism was suggested that the inclusion complex acid system may open up for a new possibility to exhibit greater acidizing performance in high day content, high-temperature, and low-permeability oil reservoirs, which contributes to improving core permeability and enhancing oil recovery.