The present disclosure discloses an air-interface-based synchronization method, a base station and its control apparatus, and a wireless communications system. By taking advantage of active random access of user equipment, a time difference between base stations is acquired by detecting a random access preamble, and a time adjustment value of a non-reference base station is acquired according to the acquired time difference and reference time of a reference base station; and the non-reference base station performs time adjustment according to the acquired time adjustment value, to complete time synchronization with the reference base station. The present disclosure can easily and effectively implement air-interface-based synchronization between base stations by using an existing wireless network, thereby achieving a technical effect in a convenient and economic manner.