A method for realizing forward channel sharing in time division communication system, which completes group configuration at the cluster control service center server and modifies the attributes of all the users to enable the users to support multi-user packet MUP service, including: (a) the cluster user initiates a group call; the access network allocates a unique group identifier MACIndex for the group call after receiving the call request from the calling cluster user and informs all of the users within the group about this MACIndex (201); (b) after the communication starts (202), the access network packets the user data of one or more groups with multi-user packet MUP, packets the user data of each group into one sub-packet and does scheduling, then transmits the packets through forward channel (203); (c) after receiving the MUP packets from the forward channel, the cluster user looks into the MUP packets for the sub-packet that matches the MACIndex of its group, thereby realizing group communication (204). The present method solves the problem of system delay and supports even more groups.