The utility model discloses a mud pump. The mud pump comprises a pump shaft, a mud pump impeller mounted at the end part of the pump shaft, an inner pump shell arranged outside the mud pump impeller in a sleeving manner, an impeller stopping nozzle which is detachably connected with the mud pump impeller, and a mud pump end cover mounted on the inner pump shell, wherein a stopping nozzle rubber gasket is arranged outside the impeller stopping nozzle in the sleeving manner; the mud pump end cover comprises a first end cover and a second end cover; the first end cover is detachably connected with the second end cover; the stopping nozzle rubber gasket is connected with the inner part of the first end cover in the sleeving manner and is detachably connected with the second end cover; the outer diameter of the stopping nozzle rubber gasket is smaller than the inner diameter of the first end cover; a mud pump lining plate is arranged between the first end cover and the mud pump impeller and is detachably connected with the first end cover; a gap is formed between the mud pump lining plate and the mud pump impeller along the axial direction. The impeller stopping nozzle and the stopping nozzle rubber gasket are replaced so that previous at least six hours are shortened to existing three hours and the working efficiency is greatly improved; no heavy large-size pieces are not used in a detaching process so that the mud pump is easy to hoist and has high safety.