Abstract: The principle for and the difficulties encountered with thread repairing are analyzed.A lso described are the CCD camera，the photoelectric encoder，repairing of the FAGOR system，and the conventional thread repair method as involving synchronization between the positioning plate and the CCD camera.A method for repairing the upset tubing thread with the CNC lathe is proposed.The CNC lathe-adopting method for thread repair can make it possible to ensure that under the precondition that theminimum dimensions of the tubing’s upset part is guaranteed，the thread is repaired on the original thread enveloping line so as the cropping loss is reduced，thus the economic benefit increased.Compared with the conventional thread repairmethod，the abovementioned method features such advantages as easy operation，zero investment，and in-lot repair operation.