The invention discloses an automatic sweeping method for air replaced with nitrogen in a blast furnace gas energy recovery system pipe network. The method controls various units arranged in the blast furnace gas energy recovery system pipe network by adopting a PLC (Programmable Logic Controller) or a DSC (Distributed Control System), monitors and controls corresponding devices one by one according to an automatic sweeping flow sequence by the PLC and the DSC, and finally finishes the automatic sweeping function to the air replaced with nitrogen in the blast furnace gas energy recovery systempipe network. The invention has the remote automatic sweeping function for the air replaced with nitrogen and has the advantages of decreasing the operation cost of a user and avoiding personal risks.