A resource allocation indication method, a device, and a system are provided. The method includes: obtaining, by a terminal device, first indication information; and determining, by the terminal device, a target resource based on the first indication information, and sending uplink data on the target resource, where the target resource includes a resource block in M basic resource units that is allocated to the terminal device; a position of an allocated resource block in each of the M basic resource units corresponds to a first frequency domain position of a resource block in a first resource block set; the first frequency domain position is a frequency domain position obtained after a second frequency domain position of a resource block in a second resource block set is shifted; and the M basic resource units are arranged in ascending order in frequency domain.