The invention provides a cleaning solution for purging filter paper of a waste air filter and relates to the technical field of filter paper recycling. The cleaning solution is prepared from the following raw materials in a weight ratio through mixing: 18% of ethyl alcohol, 3% of ceramic powder and 79% of water. Recovered filter paper is purged repeatedly by high-pressure nitrogen flow, filtered objects on the surface and in gaps of the filter paper are removed, then the gaps of the filter paper are repaired with a repairing liquid, and the original air filtering effect of the air filter is recovered. In the cleaning solution, ceramic particles are taken as a kinetic energy carrier for impact stripping, the ethyl alcohol has a softening effect on the filter paper while the filtered objects are stripped through impact, and airflow and the filtered objects penetrate the gaps of the filter paper easily; fibers forming the filter paper are not broken easily.