The embodiment of the invention provides a vibration state monitoring method and device for a variable speed rotating machinery. The method comprises steps: during a process of increase to an upper limit rotating speed from a lower limit rotating speed in a normal state of the machinery, a vertical vibration speed, a horizontal vibration speed and a rotating speed of the machinery are acquired synchronously; the vertical vibration speed and the horizontal vibration speed are integrated, a vibration root mean square value of the integrated vibration speed is extracted, and mean and variance ofthe vibration root mean square value are determined; relation curves between the mean and the variance and the rotating speed are fit respectively to acquire corresponding continuous functions; the continuous functions are substituted to a preset decision function to acquire an alarm threshold model; and the vibration root mean square value and the rotating speed of the machinery currently are acquired in real time and are substituted to the alarm threshold model to acquire the current vibration state of the machinery. The embodiment of the invention can improve the variable speed rotating machinery vibration state alarm accuracy.