Abstract: A detection device and method for measuring anaerobic ammonium oxidation activity. The detection device comprises a reactor and a detector; the reactor comprises a first reaction chamber and a second reaction chamber; the first reaction chamber is used for an anaerobic ammonium oxidation reaction and a denitrification reaction of sludge to be tested; the second reaction chamber is used for a denitrification reaction of said sludge; and the detector is used for controlling and recording the flow rates of chemicals entering the first reaction chamber and the second reaction chamber, ensuring that the pH values of the first reaction chamber and the second reaction chamber are constant and the same.