Abstract: The influence of the gyroscopic effect produced by the spindle rotation on the cutting chatter stability boundary is studied in this paper, based on a rotating model of the spindle, the tool holder and the tool. In the model, the Euler-Bernoulli cantilever beam theory is adopted to obtain the transfer function of the cutting system with consideration of the gyroscopic effect, as well as to determine the stability of the high speed cutting system.The results show that the gyroscopic effect affects the critical cutting depth of the high speed milling. With the consideration of the gyroscopic effect, when the tooth number of the tool increases, the critical cutting depth decreases. Meanwhile, the critical cutting depth decreases with the decrease of the stiffness of the system and the damping ratio of the system.