Embodiments of this application provide a parameter determining method, a base station, and user equipment. The parameter determining method provided in this application includes: determining, by a base station, a first subcarrier spacing corresponding to UE; and notifying, by the base station, the UE of the first subcarrier spacing. In the embodiments of this application, the UE may accurately learn of, in a multi-subcarrier-spacing system, a subcarrier spacing used for data transmission, and then perform data transmission. This can effectively ensure that the UE performs a corresponding service, thereby meeting a corresponding service requirement.