At the request of our customers, we have developed a high-speed electric spindle with a precision online balancing system. The maximum speed of the spindle is 12,000r/min, the power is 16kW, and the balancing accuracy reaches 0.1 micron vibration amplitude (@6,000r/min), which meets the requirements of precision grinding (vibration amplitude <2 micron). This spindle system can be used in applications such as precision gears and high-precision cylindrical grinding. The internal grinding on-line balancing system spindle can also be developed according to user requirements.