The invention discloses an automatic sweeping method for nitrogen replaced with air 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 nitrogen replaced with air in the blast furnace gas energy recovery systempipe network. The invention has the remote automatic sweeping function for the nitrogen replaced with air and has the advantages of decreasing the operation cost of a user and avoiding personal risks.