The invention relates to a repairing method capable of prolonging the service life of an RH ladle working lining, which comprises the following steps: an off-line minor repair for the first time, an off-line medium repair for the second time, an off-line minor repair for the third time, and an off-line heavy repair for the fourth time. When the eroded defect thickness of 2 to 3 layers of magnesiacarbon bricks on the lower part of a ladle lining slag line is 10 to 20 millimeters larger than the smallest replaceable defect thickness, the minor repairs for the first and the third times are performed; and when the slag line of the working lining erodes to the smallest defect thickness for exceeding 0 to 10 millimeters, the medium repair for the second time and the heavy repair for the fourthtime are performed. The method performs the planned repairs through reasonably controlling the eroded defect thickness of the ladle working lining, and changes the repairing process of two times intofour times, thus the service life of the ladle working lining is prolonged by more than one fold.