A method for monitoring the managed devices comprises that the manage center preserves the integrality list in advance, which includes the system integrality values of the managed devices and the corresponding relations of the managed devices and the system integrality values of themselves, and the managed device gathers the current system integrality value of itself and saves it when it starts; the managed device sends the information including the current system integrality value to the manage center after receiving the monitor command from the manage center; the manage center determines whether the received current system integrality value of the managed device coincides with the integrality value of the managed device saved by itself according to the received information and said integrality list, and implements the alert process when they do not coincide with each other. The manage center can know whether the managed device is believable currently so that the manage center can determine whether the unknown attack to the managed device exists or not according to the present invention.