This book presents the latest information on the intelligent CNC machine tool spindle system, which integrates various disciplines such as mechanical engineering, control engineering, computer science and information technology. It describes a prediction method and model for temperature rise and thermal deformation in motorized spindles and proposes an intelligent stator resistance identification method to reduce the torque ripple of motorized spindles under direct torque control. Further, it discusses the on-line dynamic balance method for NC machine tool spindles. The biogeographic optimization algorithm and hybrid intelligent algorithm presented here were first applied in the field of motorized spindle performance control. In turn, the book presents extensive motorized