The present invention provides a method as regards how a network side gets a MSS into the idle mode in a wireless MAN, including: the PA/BS sends a DREG_CMD to the MSS; the MSS sends a DREG_REQ message to the PA/BS, according to the DREG_CMD message, requesting to enter the idle mode; the PA/BS releases the link of the MSS and updates the data of the anchor PC/LR after receiving the DREG_REQ message. The present invention specifies the process of a MSS entering the idle mode initiated by the network and the settings of relevant parameters, thus enhancing the stability of the process of entering the idle mode and saving the system resources.