A method for calibrating downlink channels of smart antennas, comprising: allocating a downlink time-domain calibration sequence for each corresponding to-be-calibrated downlink channel according to a downlink calibration instruction; simultaneously acquiring a plurality of downlink time-domain calibration sequences corresponding to to-be-calibrated downlink channels in a period of each subsequent downlink GAP, and transmitting each of the acquired downlink time-domain calibration sequences to the corresponding downlink channel until all the allocated downlink time-domain calibration sequences are transmitted; collecting the downlink time-domain calibration sequence passing through each downlink channel in real time for each downlink GAP, performing coupling processing on the collected downlink time-domain calibration sequences to generate downlink comprehensive time-domain calibration sequences, transmitting the downlink comprehensive time-domain calibration sequences to downlink calibration channels, converting the downlink comprehensive time-domain calibration sequences passing through the downlink calibration channels into downlink comprehensive frequency-domain calibration sequences, and caching the downlink comprehensive frequency-domain calibration sequences; and calculating compensation values of the to-be-calibrated downlink channels according to all the cached downlink comprehensive frequency-domain calibration sequences, and performing online calibration on each of the to-be-calibrated downlink channels according to the compensation values; characterized in that, after the allocating the corresponding downlink time-domain calibration sequence for the each to-be-calibrated downlink channel according to the downlink calibration instruction, the method further comprises: dividing the to-be-calibrated downlink channels into multiple groups according to a preset strategy, wherein each group comprises a plurality of downlink channels, the plurality of downlink time-domain calibration sequences acquired in a period of each subsequent downlink GAP are downlink time-domain calibration sequences corresponding to one group of downlink channels in the multiple groups of downlink channels, and the downlink time-domain calibration sequences corresponding to the one group of downlink channels are transmitted in the each downlink GAP. allocating a downlink time-domain calibration sequence for each corresponding to-be-calibrated downlink channel according to a downlink calibration instruction; simultaneously acquiring a plurality of downlink time-domain calibration sequences corresponding to to-be-calibrated downlink channels in a period of each subsequent downlink GAP, and transmitting each of the acquired downlink time-domain calibration sequences to the corresponding downlink channel until all the allocated downlink time-domain calibration sequences are transmitted; collecting the downlink time-domain calibration sequence passing through each downlink channel in real time for each downlink GAP, performing coupling processing on the collected downlink time-domain calibration sequences to generate downlink comprehensive time-domain calibration sequences, transmitting the downlink comprehensive time-domain calibration sequences to downlink calibration channels, converting the downlink comprehensive time-domain calibration sequences passing through the downlink calibration channels into downlink comprehensive frequency-domain calibration sequences, and caching the downlink comprehensive frequency-domain calibration sequences; and calculating compensation values of the to-be-calibrated downlink channels according to all the cached downlink comprehensive frequency-domain calibration sequences, and performing online calibration on each of the to-be-calibrated downlink channels according to the compensation values; characterized in that, after the allocating the corresponding downlink time-domain calibration sequence for the each to-be-calibrated downlink channel according to the downlink calibration instruction, the method further comprises: dividing the to-be-calibrated downlink channels into multiple groups according to a preset strategy, wherein each group comprises a plurality of downlink channels, the plurality of downlink time-domain calibration sequences acquired in a period of each subsequent downlink GAP are downlink time-domain calibration sequences corresponding to one group of downlink channels in the multiple groups of downlink channels, and the downlink time-domain calibration sequences corresponding to the one group of downlink channels are transmitted in the each downlink GAP.