To investigate the dynamic stiffness of the rotating spindle, a non-contact loading method is applied. A magnetic loading device is used to provide swept-sine-wave load, while the spindle displacement is measured with eddy-current-type sensors. Frequency responses of the compliance are then measured, while spindle speeds and warm-up conditions are designed to regulate the temperature status in the spindle. The spindle temperature effects on the natural frequency and peak value are discussed based on the measurement results. (C) 2014 Published by Elsevier B.V.