The invention relates to a starting and stopping intelligent judging method of a rotating machinery monitoring system. According to the method, when the rotating speed of equipment is in a certain range and is stabilized for a period of time, the condition that the equipment enters a normal operation state is judged, the process of the rotating speed from the stopping to the normal operation state is judged as a starting process, and the process of the rotating speed from the normal operation state to the stopping process is judged as a stopping process. The method has the advantages that the starting and stopping judgment when the operation rotating speed of rotating machinery is lower than the rated rotating speed for a long time can be handled, and different data collection and storage methods can be respectively adopted for the starting and stopping state and the normal operation state.