Despite the successful commercialization of Cu-SSZ-13 catalysts as efficient ammonia-selective catalytic reduction (NH3-SCR) catalysts in diesel vehicles for NOx elimination, their sensitivity toward phosphorus poisoning is one of the primary challenges to practical applications. In this study, an efficient method was used to regenerate a phosphorus-poisoned Cu-SSZ-13 catalyst by washing with hot water. The mechanism of deactivation and regeneration of the Cu-SSZ-13 catalyst was deeply investigated by a series of careful characterizations of fresh, poisoned, and regenerated catalysts. After regeneration, the recovery of the decreased accessibility and porosity, deactivated Brensted acid sites, and Cu2+ ions resulted in the restoration of the decreased activity and hydrothermal stability of the poisoned Cu-SSZ-13. At a low phosphorus loading (0.2 mmol/g(catal), 0.54 wt %), the promotion effect of phosphorus on the SCR performance was observed after regeneration, which was attributed to the decrease in the content of CuO species and recovery of the acid sites and active Cu2+ ions after regeneration. Additionally, the combination of washing with hot water and hydrothermal aging results in good recovery of the SCR performance of the phosphorus-poisoned catalyst. This work focuses on the regeneration of a phosphorus-poisoned Cu-SSZ-13 catalyst, which provides an efficient method to prolong the lifespan of the Cu-SSZ-13 catalyst in practical applications.