Based on the mechanism of the friction torque generated by the ball screw of CNC machine tools, an analysis has been made of the factors that constitute the friction torque, followed by a review of the friction produced by the balls in the regenerator, the friction produced by the lubricant, the sliding friction and rolling friction of the balls, and the establishment of the friction torque model. The results show that the current research is still insufficient in terms of its universality, practicality, and systemicity. It is acknowledged that it will be the development trend to establish a universally applicable friction torque model, with a full consideration given to its stability and volatility.