The invention discloses a cellular denitration catalyst regenerating solution for a coal fired power plant and a regenerating method thereof. The regenerating solution comprises a cleaning solution and an activated replenishing solution, wherein the cleaning solution contains H2SO4 and an emulsifying agent S-185; the activated replenishing solution contains VOSO4 and ammonium paratungstate; and ultrasonic cleaning is adopted in the cleaning method. The regenerated catalyst has relative activity (K/Ko) of 0.95-0.99 and SO2/SO3 conversion rates of both less than 1 percent and meets the requirement on the engineering; and the regenerating process is simple in operation and is suitable for industrialized massive regeneration.