Ball spline is a new type of linear motion system, in which the steel ball loaded into the spline mother can perform smooth linear motion on the precisely ground spline shaft rolling surface while transmitting torque. Unlike traditional products, due to the application of pressure on one spline, it can perform exceptionally well in harsh usage environments such as vibration and impact loads, places that require high-precision positioning, and situations that require high-speed motion performance. In addition, when replacing the linear steel ball guide sleeve, the rated load can be increased by more than ten times under the same shaft diameter, which can make the design compact. It can also provide high safety and long service life under the action of cantilever load and torque. The ball spline is divided into three types: medium torque type, high torque type, and rotary type, which can be selected according to the purpose. In addition, various types are equipped with a variety of spline mother shapes, which can be selected according to the installation method and usage purpose. The accuracy of ball splines is divided into ordinary level (unmarked), advanced level (H), and precision level (P) based on the runout of the spline mother outer diameter relative to the spline shaft support.