Abstract: The flutters of cutting-tools in mechanical processes areinvestigated in this paper. The flutters are typically self-excitedoscillations and could be described by the well-known van der Pol equations.The analytical solutions of the van der Pol equations obtained by theaveraging method show the mechanism of the self-oscillations. A new strategyof linear feedback is developed to control the flutters. The controlstrategy could be realized by a delayed linear function. Theanalytical solutions of the van der Pol equations with delayed linear feedbackshow that the flutters could be effectivelyreduced. Numerical simulations confirm the theoretical predictions.