A method for measuring protein in sludge according to the coomassie brilliant blue method belongs to the field of influencing factors in municipal sewage treatment. After being combined with protein, coomassie brilliant blue G-250 becomes cyan, the protein-pigment combined material is highest in light absorption value under a 595nm wavelength condition, and the light absorption value is in direct proportion to protein content, the method can be used for quantitative measurement of protein. The method particularly relates to the following steps: reagent preparation, standard curve measuring, sludge pretreatment, protein extraction and measuring, and the like. The method is a simple and efficient method for measuring the protein content in sewage.