The invention provides a precision concentricity correcting tool. The tool achieves the function of correcting the concentricity between an oil bearing and a motor end cover through a correcting mandrel, achieves the positioning function by matching of an end cover base, a bearing block and a support rod, achieves the limit function by matching of a movable upper plate, a limit block and a fixed base plate, achieves the guiding function by matching of a linear guide bearing, a guide post and a limit stop, and achieves the tool resetting function by matching of a spring and a butterfly gasket.The tool can eliminate the gap between the oil bearing and the motor end cover, so that the oil bearing can be assembled into the motor end cover. The tool can further control the concentricity deviation between the oil bearing and the motor end cover to be small to ensure the assembly precision, and further ensure the normal operation of the motor and greatly prolong the service life of the motor.