A method for indicating a frequency domain resource, comprising: receiving, by a terminal device, first indication information sent by a network device, wherein the first indication information indicates, by using a first unit as granularity, whether a resource region in a system frequency domain resource comprises a target frequency domain resource allocated by the network device from the system frequency domain resource to the terminal device, wherein, the system frequency domain resource comprises multiple types of frequency domain resources, the multiple types of frequency domain resources respectively have different sub-carrier internals, the multiple types of frequency domain resources are respectively composed of minimum frequency domain scheduling units of different sizes, a size of the resource region is the same as a size of the first unit, the size of the first unit is M times a minimum frequency domain scheduling unit of a frequency domain resource having a second sub-carrier interval, M is an integer greater than or equal to 1, and the second sub-carrier interval is greater than a sub-carrier interval of the target frequency domain resource; and determining, by the terminal device, according to the first indication information, a resource region where the target frequency domain resource is located; wherein the target frequency domain resource comprises a first frequency domain resource and a second frequency domain resource, and a sub-carrier interval of the first frequency domain resource is smaller than a sub-carrier interval of the second frequency domain resource, the first indication information is configured to indicate, by the first unit, whether the resource region in the system frequency domain resource comprises the first frequency domain resource and the second frequency domain resource, and the second sub-carrier interval is greater than or equal to the sub-carrier interval of the second frequency domain resource. receiving, by a terminal device, first indication information sent by a network device, wherein the first indication information indicates, by using a first unit as granularity, whether a resource region in a system frequency domain resource comprises a target frequency domain resource allocated by the network device from the system frequency domain resource to the terminal device, wherein, the system frequency domain resource comprises multiple types of frequency domain resources, the multiple types of frequency domain resources respectively have different sub-carrier internals, the multiple types of frequency domain resources are respectively composed of minimum frequency domain scheduling units of different sizes, a size of the resource region is the same as a size of the first unit, the size of the first unit is M times a minimum frequency domain scheduling unit of a frequency domain resource having a second sub-carrier interval, M is an integer greater than or equal to 1, and the second sub-carrier interval is greater than a sub-carrier interval of the target frequency domain resource; and determining, by the terminal device, according to the first indication information, a resource region where the target frequency domain resource is located; wherein the target frequency domain resource comprises a first frequency domain resource and a second frequency domain resource, and a sub-carrier interval of the first frequency domain resource is smaller than a sub-carrier interval of the second frequency domain resource, the first indication information is configured to indicate, by the first unit, whether the resource region in the system frequency domain resource comprises the first frequency domain resource and the second frequency domain resource, and the second sub-carrier interval is greater than or equal to the sub-carrier interval of the second frequency domain resource.