Embodiments disclose a method, a device, and an apparatus for determining a downlink parameter. The method may include: receiving category information and modulation information that are reported by UE, where the category information includes a UE category of the UE, and the modulation information includes a highest order modulation scheme supported by the UE; and determining, as a downlink parameter of the UE, a downlink parameter that corresponds to the UE category of the UE and the highest order modulation scheme supported by the UE, where the downlink parameter of the UE is determined according to a correspondence from a UE category of the UE and a highest order modulation scheme supported by the UE to a downlink parameter of the UE as well as the UE category of the UE and the highest order modulation scheme supported by the UE.