Embodiments of this application disclose beam training methods, apparatuses, and systems. One method includes: receiving, from a network device, interference-related information; receiving, from the network device, a downlink signal sent through two or more beams, wherein the two or more beams comprise an interfering beam that causes interference to a terminal device; and transmitting, to the network device, information related to a beam selected from the two or more beams, wherein the beam is selected by the terminal device based on the interference-related information and a measurement result obtained from measuring the downlink signal.