Disclosed are a method and an apparatus for measuring CSI. The method comprises: a first device determining a first measurement frequency band and a second measurement frequency band, the first measurement frequency band being used for performing wideband CSI measurement, the second measurement frequency band being a used for performing sub-band CSI measurement, and a bandwidth of the first measurement frequency band being smaller than a downlink transmission bandwidth and the first measurement frequency band and the second measurement frequency band being not fully overlapped; performing wideband CSI measurement on the first measurement frequency band; and performing sub-band CSI measurement on the second measurement frequency band according a measurement result obtained in the wideband CSI measurement. According to the method and the apparatus for measuring CSI in the embodiments of the present invention, compared with a solution in which scheduling is performed when a base station cannot obtain a CSI measurement result reported by a UE, the method and the apparatus can improve the scheduling efficiency of a network side device and improve system performance and user experience.