The utility model discloses a wave subduer for a railway liquid tank wagon. The wave subduer comprises base plates fixed at both sides of the inner wall of a tank body. Two pairs of connecting plates are respectively and vertically fixed on the two base plates; and washboards in slide fit with the corresponding connecting plates are inserted between the pairs of connecting plates at both the sides. Preferably, baffles for supporting the washboards are fixed at the lower parts of the connecting plates; bolt assemblies for preventing the washboards from being separated out are arranged at the upper parts of the connecting plates; the end part of each washboard is provided with a positioning baffle; another positioning baffle is matched with each connecting plate is arranged on the connecting plate; and rib plates are arranged between the base plates and the outsides of the connecting plates. The wave subduer has the characteristic of flexible connection, is difficult to fall, is firm and reliable to fix, is convenient to overhaul and clean the tank body and is suitable to apply on the tank wagon for loading various liquid mediums; and the dynamics performance can be effectively improved, the running safety is ensured and the service life of the wagon is prolonged.