The invention provides a method for comprehensively treating grating garbage and activated sludge in a sewage plant. The pretreated grating garbage and concentrated activated sludge are mixed and the mixture and sorted organic domestic garbage are subjected to chemical catalytic hydrolysis and ammonia-fixing treatment to form an organic energy fertilizer by the prior art. The method has the advantages that: 1, the grating garbage does not need conveying outside through payment to be treated, so that the processing fee of the grating garbage is saved; 2, the activated sludge is treated by waste acid and subjected to gravity concentration, and two-step concentration (gravity settling and flocculation concentration by adding polyacrylamide) in the prior art is changed into one-step concentration, so that the equipment and material cost is saved, and the process is simple and quick and has significance for environmental protection by using the waste acid; and 3, the concentrated activatedsludge and the pretreated grating garbage are directly mixed and subjected to chemical catalytic hydrolysis, so that the dehydration process is saved, the repeated process is avoided, the floor area is reduced and the equipment investment is saved.