A measurement method, comprising: receiving, by a terminal, a switching message of a narrow-bandwidth receiving mode from a base station; switching, by the terminal, to a specified narrow bandwidth for information reception; receiving downlink control information, DCI, in a physical downlink control channel, PDCCH, on the specified narrow bandwidth, wherein the DCI is in a terminal-specific search space corresponding to the terminal and at a control channel element aggregation level corresponding to the terminal; and sequentially switching, by the terminal, to at least two different measurement narrow bandwidths according to scheduling of the base station, to measure downlink reference signals, when channel state information, CSI, of a downlink channel needs to be measured, wherein each of the specified narrow bandwidth and the at least two different measurement narrow bandwidths is smaller than a system bandwidth; and the at least two different measurement narrow bandwidths comprise the first measurement narrow bandwidth and the second measurement narrow bandwidth, and sequentially switching to the at least two different measurement narrow bandwidths according to scheduling of the base station, to measure the downlink reference signals, when the CSI of the downlink channel needs to be measured comprises: receiving first DCI sent by the base station in the PDCCH on the specified narrow bandwidth, wherein the first DCI comprises bandwidth information of the first measurement narrow bandwidth, and starting time and ending time for measurement on the first measurement narrow bandwidth, and switching to the first measurement narrow bandwidth to measure the downlink reference signals; and after completion of measurement on the first measurement narrow bandwidth and switching back to the specified narrow bandwidth, receiving second DCI sent by the base station in the PDCCH on the specified narrow bandwidth, wherein the second DCI comprises bandwidth information of the second measurement narrow bandwidth, and starting time and ending time for measurement on the second measurement narrow bandwidth, and switching to the second measurement narrow bandwidth to measure the downlink reference signals. receiving, by a terminal, a switching message of a narrow-bandwidth receiving mode from a base station; switching, by the terminal, to a specified narrow bandwidth for information reception; receiving downlink control information, DCI, in a physical downlink control channel, PDCCH, on the specified narrow bandwidth, wherein the DCI is in a terminal-specific search space corresponding to the terminal and at a control channel element aggregation level corresponding to the terminal; and sequentially switching, by the terminal, to at least two different measurement narrow bandwidths according to scheduling of the base station, to measure downlink reference signals, when channel state information, CSI, of a downlink channel needs to be measured, wherein each of the specified narrow bandwidth and the at least two different measurement narrow bandwidths is smaller than a system bandwidth; and the at least two different measurement narrow bandwidths comprise the first measurement narrow bandwidth and the second measurement narrow bandwidth, and sequentially switching to the at least two different measurement narrow bandwidths according to scheduling of the base station, to measure the downlink reference signals, when the CSI of the downlink channel needs to be measured comprises: receiving first DCI sent by the base station in the PDCCH on the specified narrow bandwidth, wherein the first DCI comprises bandwidth information of the first measurement narrow bandwidth, and starting time and ending time for measurement on the first measurement narrow bandwidth, and switching to the first measurement narrow bandwidth to measure the downlink reference signals; and after completion of measurement on the first measurement narrow bandwidth and switching back to the specified narrow bandwidth, receiving second DCI sent by the base station in the PDCCH on the specified narrow bandwidth, wherein the second DCI comprises bandwidth information of the second measurement narrow bandwidth, and starting time and ending time for measurement on the second measurement narrow bandwidth, and switching to the second measurement narrow bandwidth to measure the downlink reference signals. receiving second DCI sent by the base station in the PDCCH on the specified narrow bandwidth, wherein the second DCI comprises bandwidth information of the second measurement narrow bandwidth, and starting time and ending time for measurement on the second measurement narrow bandwidth, and switching to the second measurement narrow bandwidth to measure the downlink reference signals.