Abstract: Disclosed in the present invention is a signal transmission method for a multi-antenna multi-user TDD communication system. Each frame of the TDD communication system includes one forward downlink frame synchronization signal, multiple downlink data time slots, and multiple uplink data time slots; the downlink frame synchronization signal is a broadcast signal, the base station sends the downlink frame synchronization signal to all terminals, and after each terminal receives the downlink frame synchronization signal, time and frequency synchronization is performed with reference to the base station to acquire the start time and end time of each uplink data time slot. The synchronization signal received power P is evaluated and compared with the synchronization signal received power range of all uplink data time slots in the frame, and all terminals falling into the synchronization signal received power range of the uplink data time slot k select the uplink data time slot k to send data.