The present invention discloses a system for monitoring dynamic stability of micro machine is provided in this invention, wherein an image-capturing device and an analytic device are included. The image-capturing device captures an image on a surface of a work piece milled by the micro machine. The analytic device comprises an image input interface, means for gray-scaling an image, means for analyzing abnormal gray-scaled value of the gray-scaled image, and means for analyzing numbers of veins of the gray-scaled image. This invention also provides a method for monitoring dynamic stability of micro machine.