The utility model discloses an alkali polishing tank with a filtering device. Alkali polishing tank main tank, a loop is formed outside the alkali polishing tank main tank and inside the alkali polishing tank main tank through a circulating pipe; a filtering device is mounted on the circulating pipe, the filtering device comprises a filtering box and a filtering element extending into the filtering box, liquid medicine in the alkali polishing groove main groove enters the filtering box through the circulating pipe, the liquid medicine is filtered by the filtering element, the filtered liquid medicine enters the alkali polishing groove main groove again through the circulating pipe, and the alkali polishing groove main groove is further provided with a liquid supplementing opening; according to the utility model, the filtering device is additionally arranged outside the main tank of the alkali polishing tank, dirt and colloid products are blocked in the filtering box, and meanwhile, thefiltering area and the liquid supplementing area are separated, so that the liquid supplementing effect is prevented from being influenced by the reaction of newly added liquid medicine and the dirt;liquid medicine in the main tank of the alkali polishing tank flows out of the main tank, is pressurized by the circulating motor, is pumped into the filtering device, is filtered and then flows intothe main tank.