A method for inserting a downlink common pilot, which is adaptable to the OFDMA TDD system, the method comprising: A: dividing data to be transmitted into several segments to be transmitted in several continuous time periods, each scheduled time period comprising several slots with at least one downlink slot; the method further comprising: B: inserting a common pilot in one downlink slot in a scheduled time period; wherein the scheduled time period comprises slots in one or more frames wherein when the TDD system based on OFDMA adopts the same frame structure as the TD-SCDMA system composed of 7 normal slots, TS0 - TS6, a downlink pilot timeslot, DwPTS, an uplink pilot timeslot, UpPTS, and a guard period, GP, and when in each sub-frame of the TD-SCDMA system, normal slots TS0, TS4, TS5 and TS6 are downlink slots and TS1, TS2 and TS3 are uplink slots, TS4, TS5 and TS6 in each sub-frame and TS0, DwPTS, GP, UpPTS, TS1, TS2, and TS3 in a subsequent sub-frame are allocated into a scheduled time period and a downlink common pilot is inserted into one of the TS0 and DwPTS in each scheduled time period; or when in each sub-frame of the TD-SCDMA system, normal slots TS0, TS2, TS3, TS5, and TS6 are downlink slots and TS1 and TS4 are uplink slots, TS5 and TS6 in each sub-frame and TS0, DwPTS, GP, UpPTS, and TS1 in a subsequent sub-frame are allocated into a time period a and TS2, TS3, TS4 are allocated into a time period b, a downlink common pilot is inserted into one of the TS0 and DwPTS in the scheduled time period a and a downlink common pilot is inserted into the TS3 in the scheduled time period b; or when in each sub-frame of the OFDMA TDD system, normal slots TS0, TS2, TS4 and TS6 are downlink slots and TS1, TS3 and TS5 are uplink slots, TS6 in each sub-frame and TS0, DwPTS, GP, UpPTS and TS1 in a subsequent sub-frame are allocated into a time period c, TS2 and TS3 are allocated into a time period d, and TS4 and TS5 are allocated into a time period e, a downlink common pilot is inserted into one of the TS0 and DwPTS in the scheduled time period c, a downlink common pilot is inserted into the TS2 in the scheduled time period d and a downlink common pilot is inserted into the TS4 in the scheduled time period e. A: dividing data to be transmitted into several segments to be transmitted in several continuous time periods, each scheduled time period comprising several slots with at least one downlink slot; the method further comprising: B: inserting a common pilot in one downlink slot in a scheduled time period; wherein the scheduled time period comprises slots in one or more frames wherein when the TDD system based on OFDMA adopts the same frame structure as the TD-SCDMA system composed of 7 normal slots, TS0 - TS6, a downlink pilot timeslot, DwPTS, an uplink pilot timeslot, UpPTS, and a guard period, GP, and when in each sub-frame of the TD-SCDMA system, normal slots TS0, TS4, TS5 and TS6 are downlink slots and TS1, TS2 and TS3 are uplink slots, TS4, TS5 and TS6 in each sub-frame and TS0, DwPTS, GP, UpPTS, TS1, TS2, and TS3 in a subsequent sub-frame are allocated into a scheduled time period and a downlink common pilot is inserted into one of the TS0 and DwPTS in each scheduled time period; or when in each sub-frame of the TD-SCDMA system, normal slots TS0, TS2, TS3, TS5, and TS6 are downlink slots and TS1 and TS4 are uplink slots, TS5 and TS6 in each sub-frame and TS0, DwPTS, GP, UpPTS, and TS1 in a subsequent sub-frame are allocated into a time period a and TS2, TS3, TS4 are allocated into a time period b, a downlink common pilot is inserted into one of the TS0 and DwPTS in the scheduled time period a and a downlink common pilot is inserted into the TS3 in the scheduled time period b; or when in each sub-frame of the OFDMA TDD system, normal slots TS0, TS2, TS4 and TS6 are downlink slots and TS1, TS3 and TS5 are uplink slots, TS6 in each sub-frame and TS0, DwPTS, GP, UpPTS and TS1 in a subsequent sub-frame are allocated into a time period c, TS2 and TS3 are allocated into a time period d, and TS4 and TS5 are allocated into a time period e, a downlink common pilot is inserted into one of the TS0 and DwPTS in the scheduled time period c, a downlink common pilot is inserted into the TS2 in the scheduled time period d and a downlink common pilot is inserted into the TS4 in the scheduled time period e.