A real-time calibration method for a smart antenna array. The method includes: before installation, a smart antenna array is pre-calibrated to obtain transmission-coefficient matrix between antenna units; after installation at site, the pre-calibrated transmission-coefficient matrix is loaded in a base station to which the smart antenna array connects; during running, every transmission link of the base station transmits a unit calibration signal in sequence in a time-slot, and all other links, except the transmitting link, are in a reception state to receive the unit calibration signal, and the received unit calibration signals are recorded; with the received unit calibration signals and pre-calibrated transmission-coefficient matrix, the smart antenna array is calibrated. The method does not need beacon antenna, coupled structure of the antenna array and a special calibration link.