The invention provides a method for improving the content of humic acid in weathered coal and belongs to the technical field of humic acid preparation. According to the invention, the method for improving the content of humic acid in the weathered coal is provided so that the problem that the existing humic acid production rate is low is solved. The adopted technical scheme comprises the following method steps: firstly, preparing a mixed additive, namely, adding non-polar oil into a reactor for heating, then adding organic acid, stirring, further heating and carrying out heat preservation, adding a foaming agent and then adding a reinforcing agent, and evenly mixing, and separating impurities so as to obtain the mixed additive; and introducing air into a drying tube and heating the weathered coal in the drying tube, adding the weathered coal into a flotation cell of a flotation machine, sufficiently wetting the weathered coal and then adding the mixed additive into the flotation cell, inflating and scrapping foam, and finally carrying out suction filtration on coal slurry and drying. The method provided by the invention is applied to the technical field of improvement of the content of humic acid in the weathered coal.