The invention discloses a reactive muffler for an engineering machine, which comprises a flange plate, a connecting pipe, a barrel and a smoke exhaust pipe. The inside of the barrel is sequentially divided into a cavity I, a cavity II and a cavity III by a front partition board and a rear partition board from front to back, two first sound attenuation barrels which are positioned in the cavity I and the cavity II are disposed on the front partition board, two second sound attenuation barrels are arranged in the cavity II, a third sound attenuation barrel is disposed in the cavity III, the first sound attenuation barrels and the second sound attenuation barrels are arranged along the axial direction of the barrel, the third sound attenuation barrel is perpendicular to the first sound attenuation barrels and the second sound attenuation barrels, the connecting pipe and the smoke exhaust pipe are perpendicularly connected onto the barrel and are spatially perpendicularly arranged in a crossed manner, the connecting pipe is communicated with the cavity I, the smoke exhaust pipe is communicated with the cavity III, and the flange plate is connected with the cavity I via the connecting pipe. The reactive muffler is reasonable in structure, fine in acoustic performance and long in service life, regenerated noise of airflow is low, and a muffler effect for low, medium and high-frequency noise of exhaust of an engine is remarkable.