Backflushing filtering tank

The utility model discloses a back-flushing filtering tank which comprises a tank body, a filtering device, a back-flushing water pipe, a filtering water outlet pipe and a water inlet pipe, the bottom of the tank body is in a cone shape with the diameter gradually reduced from top to bottom, and a sewage outlet capable of being opened and closed is formed in the lowest point of the tank body; the water inlet pipe penetrates into the tank body from the outside of the tank body, a plurality of uniformly distributed branch pipes are arranged on a pipe section, positioned at the upper part in the tank body, of the water inlet pipe, and a plurality of water inlets are formed in each branch pipe; the filtering device is installed in the middle of the interior of the tank body and located between the water inlet and the sewage outlet and comprises a positioning frame and multiple rows of filtering pipes, the positioning frame is of a hollow structure, the filtering pipes are connected to the positioning frame and co