The motorized spindles are equipped with built-in motors for better power transmission and balance to achieve high-speed operation .The thermal deformation of the spindle owe to the heat decreases the accuracy of high-speed machine tool greatly. The dynamic characteristics are affected by thermal load, preload, centrifugal and gyroscopic effects. So the Finite element analysis is important to characterize the thermal and dynamic behavior of the high speed motorized spindle. The methodology for the thermal and dynamic analysis is arrived from the literature survey. Thermal analysis is conducted for finding temperature distribution, radial and axial deflection due to thermal load for different operating speeds in high speed motorized spindle using ANSYS. The temperatures which are taken from the ANSYS results at bearings and motor location in the high speed motorized spindle are validated with the data which are taken experimentally. Modal analysis is performed for finding natural frequencies and corresponding mode shapes of the high speed motorized spindle with the effect of the axial preload, centrifugal and gyroscopic effects using ANSYS.