A method, an apparatus and a system for sharing a subchannel are disclosed. The method includes: obtaining downlink state information and uplink state information of a subchannel; and scheduling the subchannel according to the downlink state information and uplink state information of the subchannel, and allocating the subchannel to an uplink Mobile Station (MS) and/or a downlink MS. The method improves efficiency and flexibility of sharing subchannels, and therefore improves overall traffic significantly.