Biochemical filtering box

The utility model discloses a novel biochemical filtering box arranged inside an aquarium. The inner part of the box body is divided into a main filtering cavity and a purified water storing cavity by a water stop sheet and a water leak sheet; The filtering water filtered and nitrified by the main filtering cavity is forced to flow into the purified water storing cavity, then is pumped outside the box by an air-lifting type water pumping device or a diving pump, and then is driven to do filtering circulation with water in an aquarium. The main filtering cavity of the novel biochemical filtering box is oppositely independent with other parts, so that when the novel biochemical filtering box is cleaned, filtering devices arranged at the lower part of the main filtering cavity, and a nitrifying system arranged in the filtering devices do not to be moved to cause biochemical filtering function weaken or ineffective.