Based on the principle of error in position feedback control system, and the definition of the angle of twist and its relation with rifling equation, analyze influence from following error of tool bar rotation angle to indexes like angle of twist precision and width of different rifling, which are in the process of rifling broaching of the LK6/LK8 CNC deep-hole helical broaching machine when adopting C=F(z), the linkage algorithm. Present computational formula between the following error and parameters such as pulling velocity, angle of twist, caliber of tube, servo gain, as well as measures to reduce its effect. The method is proved to be accuracy and effective during application, and could be made reference to error analysis of similar algorithm during broaches of the deep-hole variational section slot.