A communication beam determining method, comprising: respectively sending, by a network side device, downlink sounding signals by using M beams with a first width, wherein main lobe directions of any two of the M beams with the first width are different, and M is not less than 2; receiving, by the network side device, sounding results of the downlink sounding signals and that are returned by user equipment, UE, and determining N beams with a second width based on the sounding results, wherein the second width is less than the first width, a coverage area of a set of the N beams with the second width is smaller than a coverage area of a set of the M beams with the first width, and N is not less than 2; and respectively sending, by the network side device, downlink scanning signals by using the N beams with the second width, and determining, based on scanning results that are of the downlink scanning signals and that are returned by the UE, a first beam for data transmission with the UE; wherein after the determining, by the network side device, the first beam, the method further comprises: obtaining, by the network side device, channel change information of the UE wherein the channel change information is reported to the network side device by the UE, or is determined by the network side device based on an uplink signal sent by the UE; generating, by the network side device, at least two tracking beams based on spatial channel area information of the UE, corresponding to the spatial channel area in which the UE is located, derived from the channel change information and the first beam wherein a set of the at least two tracking beams conforms to a movement status of the UE and a coverage area of the set conforms to the spatial channel area information of the UE; and respectively sending, by the network side device, downlink tracking signals by using the at least two tracking beams, and updating, based on tracking results that are of the downlink tracking signals and that are returned by the UE, the beam for data transmission with the UE. respectively sending, by a network side device, downlink sounding signals by using M beams with a first width, wherein main lobe directions of any two of the M beams with the first width are different, and M is not less than 2; receiving, by the network side device, sounding results of the downlink sounding signals and that are returned by user equipment, UE, and determining N beams with a second width based on the sounding results, wherein the second width is less than the first width, a coverage area of a set of the N beams with the second width is smaller than a coverage area of a set of the M beams with the first width, and N is not less than 2; and respectively sending, by the network side device, downlink scanning signals by using the N beams with the second width, and determining, based on scanning results that are of the downlink scanning signals and that are returned by the UE, a first beam for data transmission with the UE; wherein after the determining, by the network side device, the first beam, the method further comprises: obtaining, by the network side device, channel change information of the UE wherein the channel change information is reported to the network side device by the UE, or is determined by the network side device based on an uplink signal sent by the UE; generating, by the network side device, at least two tracking beams based on spatial channel area information of the UE, corresponding to the spatial channel area in which the UE is located, derived from the channel change information and the first beam wherein a set of the at least two tracking beams conforms to a movement status of the UE and a coverage area of the set conforms to the spatial channel area information of the UE; and respectively sending, by the network side device, downlink tracking signals by using the at least two tracking beams, and updating, based on tracking results that are of the downlink tracking signals and that are returned by the UE, the beam for data transmission with the UE. obtaining, by the network side device, channel change information of the UE wherein the channel change information is reported to the network side device by the UE, or is determined by the network side device based on an uplink signal sent by the UE; generating, by the network side device, at least two tracking beams based on spatial channel area information of the UE, corresponding to the spatial channel area in which the UE is located, derived from the channel change information and the first beam wherein a set of the at least two tracking beams conforms to a movement status of the UE and a coverage area of the set conforms to the spatial channel area information of the UE; and respectively sending, by the network side device, downlink tracking signals by using the at least two tracking beams, and updating, based on tracking results that are of the downlink tracking signals and that are returned by the UE, the beam for data transmission with the UE.