This disclosure provides a measurement method, a terminal device, and an access network device. The method includes: receiving, by a terminal device, a first message sent by an access network device, where the first message includes measurement type information, the measurement type information is used to indicate a first measurement granularity, and the first measurement granularity is one of a cell measurement granularity or a beam measurement granularity; and obtaining, by the terminal device, a measured value of a measurement object corresponding to the first measurement granularity. In the embodiments of this disclosure, by introducing different measurement type information, measurement of different granularities may be implemented, so that the measurement granularity is more refined and measurement results are more accurate.