In high speed milling aeronautical part,tool condition monitoring(TCM)is very impor-tant,because it is prone to get a chatter owing to the low stiffness of thin-walled structures.And the TCM is key technology for automated machining.In this paper,aiming to chatter monitoring in thin-walled structure milling,a variational mode decomposition-energy distribution(VMD-ED)method is proposed to improve the identification accuracy.And a moving average root mean square-mean value(MARMS-MV)identification method and a variational mode decomposition-energy entropy(VMD-EE)identification method are also tested.Identification accuracy and com-puting time of the three methods are compared.The vibration signals collected from the spindle and worktable are also contrasted.The conducted experimental study shows that,the proposed VMD-ED method offers an identification method for chatter monitoring with greater sensitivity,better stability and less computing time,and mounting the vibration sensor on worktable is better than spindle for a chatter monitoring system.