Embodiments of the present invention provide a method and an apparatus for calibrating a channel between RRUs. The method includes: for each subcarrier in M subcarriers in full bandwidth, instructing, by a BBU, a reference RRU to transceive a calibration signal on the subcarrier by using a reference channel and a preset channel in a preset RRU, and calculating a calibration coefficient; and determining a first correspondence according to M calibration coefficients obtained by means of calculation, where the first correspondence includes a correspondence between a frequency of each subcarrier and the calibration coefficient on the subcarrier, 2≤M