Embodiments of the present invention disclose a transmit diversity method, a related device, and a system, which mainly includes: configuring two different antenna ports separately for different antennas in a network, so that the antennas can use transmit diversity based on the configured antenna ports. In one aspect, because two antenna ports are used in the network to perform transmit diversity, a diversity gain of multiple antennas is obtained. In another aspect, a cavity position caused by a completely identical precoding codebook used in the network is avoided, and therefore network communication performance is improved. The technical solutions according to the embodiments of the present invention efficiently use the transmit diversity of the multiple antennas to acquire diversity gain so as to improve network communication performance.