<p>RuO₂ /TiO₂, as the main catalyst in wet catalytic oxidation, faces the problem of catalyst deactivation while treating high concentration organic wastewater efficiently and without pollution. There have been many studies on catalyst deactivation and regeneration, but most of them are based on laboratory simulation environment. Due to the complexity of industrial environments, the causes of industrial catalyst deactivation are still unclear, while there are very few studies on regeneration. Herein, we characterized industrially used catalysts and found that the causes of catalyst deactivation can be attributed to two reasons, namely, the change of carrier crystal shape and carbon accumulation. Thermal regeneration to address the carbon accumulation problem restores some of the physicochemical properties of the used catalysts, however, thermal regeneration cannot restore the catalyst support phase from rutile back to anatase, resulting in the inability to restore catalyst activity. Therefore, the catalyst was regenerated by the method of direct addition of active components, and the catalyst activity was basically restored when the Ru mass fraction was 0.5%. Moreover, the method of directly adding active components has the advantages of simplicity and no energy consumption, which is easy to be utilized in the industrial production process.</p> Graphical Abstract <p></p>