A terminal device reports a measurement capability to a network side, and the network side determines, based on the capability of the terminal device and a trigger condition, whether a measurement gap needs to be allocated to the terminal device, where the measurement gap is used by the terminal device to measure an inter-frequency or inter-RAT cell. When the network side allocates the measurement gap to the terminal device, and when the terminal device determines that an objective of not allocating a gap can be achieved by de-configuring a secondary cell or reducing a data receiving rule of a currently camped-on cell. When an inter-frequency or inter-RAT cell is measured by de-configuring the secondary cell or reducing the data receiving rule of the currently camped-on cell, a cell measurement task can be completed.