A wireless communications method and a wireless communications system are disclosed. In an embodiment, the system includes a transmit end including a transmit module having at least two antenna units, the transmit module is configured to transmit M narrow beams with different spatial directions according to a quality of service requirement, and switches a transmit mode according to a preset switching rule, wherein a set of the spatial directions of the M narrow beams forms a transmit mode; a receive end including a receive module having at least two antenna units, the receive module is configured to receive N beams according to the QoS requirement, and a transmission channel is formed, wherein the receive end calculates transmission channel quality in different transmit modes, searches for a transmit mode that meets the QoS requirement, and feeds back the transmit mode to the transmit end.