The invention provides a PH adjusting tank and belongs to the technical field of metal galvanization. The PH adjusting tank comprises an adjustor feeding mechanism and liquid outlet mechanisms, wherein adjustor nozzles are arranged inside a traveling bracket of the adjustor feeding mechanism; an adjustor joint is arranged outside the traveling bracket; one end of the liquid inlet pipe is connected with the adjustor joint and the other end of the liquid inlet pipe is connected with the adjustor tank; first valve elements in front and back direction and guide grooves in left and right direction are arranged in a liquid outlet valve of each of the liquid outlet mechanisms; a driven rod can be slidably arranged in the guide groove of the liquid outlet valve left and right; second valve elements corresponding to the first valve elements in quantity are arranged on the driven rod; the left and right ends of the driven rod are hinged to the lower ends of a left connecting bracket and a right connecting bracket, respectively; the upper ends of the left and right connecting brackets are hinged to a driving rod; one end of the driving rod is connected with a driving air cylinder; and a liquid outlet guide groove is formed at the lower end of the liquid outlet valve. The PH adjusting tank provided by the invention can automatically feed an adjustor and is not only simple in structure and low in cost, but also low in noise and high in production efficiency.