The invention discloses a repairing method of a scrapped mud pump cylinder sleeve. The method comprises the following steps of: rough turning the inner lining surface of the cylinder sleeve; then processing a helical welding groove by a lathe at the inner lining surface of the cylinder sleeve, and welding a welding layer at the inner lining surface of the cylinder sleeve along the helical welding groove; then carrying out appearance testing and nondestructive testing on the cylinder sleeve; if the inner lining surface and internal part of the cylinder sleeve have cracks or air holes, polishing the parts having cracks and/or air holes, and locally welding until the surface and internal part of the cylinder sleeve do not have cracks or air holes; and finally rough turning or rough grinding the spare parts of the inner lining surface of the cylinder sleeve, and fine grinding until the cylinder sleeve satisfies the appearance size and fineness requirements. The method is simple, convenient and effective in technology; by the method, the inner lining of the mud pump cylinder sleeve can be excellently repaired; and a purpose of recycling can be achieved, so that the service life of the mud pump cylinder sleeve is correspondingly prolonged, the using cost of the mud pump cylinder sleeve is fully reduced, the labor and equipment cost is low, the repairing cost is low, and the method is suitable for popularizing and spreading.