Disclosed by the present invention is a method for determining the size of a resource block group. A network device sends downlink control information (DCI) that is scrambled by a temporary identifier of a wireless network, and the terminal device determines, according to the temporary identifier of the wireless network and the size of the bandwidth part of the scrambled DCI, the size of the resource block group used for the DCI scheduling resource. The terminal device dynamically selects the frequency domain granularity for resource scheduling and allocation according to different service types, which not only improves the service capability of the terminal device, but also improves the resource utilization of an NR system. Further disclosed by the present invention are a network device, a terminal device and a storage medium.