A time synchronization method, implemented by a target base station, wherein the method comprises: receiving a handover request, from a source base station, for requesting to perform time synchronization with the target base station; and sending handover request acknowledgement information to the source base station, wherein the handover request acknowledgement information comprises information used to indicate whether the source base station performs time synchronization with the target base station; wherein before sending the handover request acknowledgement information to the source base station, the method further comprises: detecting whether a root sequence on which no preamble allocation has been performed exists in a root sequence stored in the target base station; when the root sequence on which no preamble allocation has been performed exists in the root sequence stored in the target base station, selecting a target root sequence from the root sequence on which no preamble allocation has been performed; and determining a target preamble in the target root sequence; and further wherein the sending handover request acknowledgement information to the source base station comprises: after the target base station determines the target preamble from the stored root sequence, sending the handover request acknowledgement information to the source base station, wherein the handover request acknowledgement information comprises synchronization information used to indicate time synchronization between the source base station and the target base station, the synchronization information comprises the target preamble which is a unique preamble in the target root sequence, used to uniquely identify time synchronization, in a same root sequence, the synchronization information is further used to instruct the source base station to send a handover command to user equipment, UE, and the handover command comprises the target preamble. receiving a handover request, from a source base station, for requesting to perform time synchronization with the target base station; and sending handover request acknowledgement information to the source base station, wherein the handover request acknowledgement information comprises information used to indicate whether the source base station performs time synchronization with the target base station; wherein before sending the handover request acknowledgement information to the source base station, the method further comprises: detecting whether a root sequence on which no preamble allocation has been performed exists in a root sequence stored in the target base station; when the root sequence on which no preamble allocation has been performed exists in the root sequence stored in the target base station, selecting a target root sequence from the root sequence on which no preamble allocation has been performed; and determining a target preamble in the target root sequence; and further wherein the sending handover request acknowledgement information to the source base station comprises: after the target base station determines the target preamble from the stored root sequence, sending the handover request acknowledgement information to the source base station, wherein the handover request acknowledgement information comprises synchronization information used to indicate time synchronization between the source base station and the target base station, the synchronization information comprises the target preamble which is a unique preamble in the target root sequence, used to uniquely identify time synchronization, in a same root sequence, the synchronization information is further used to instruct the source base station to send a handover command to user equipment, UE, and the handover command comprises the target preamble. detecting whether a root sequence on which no preamble allocation has been performed exists in a root sequence stored in the target base station; when the root sequence on which no preamble allocation has been performed exists in the root sequence stored in the target base station, selecting a target root sequence from the root sequence on which no preamble allocation has been performed; and determining a target preamble in the target root sequence; and further wherein the sending handover request acknowledgement information to the source base station comprises: after the target base station determines the target preamble from the stored root sequence, sending the handover request acknowledgement information to the source base station, wherein the handover request acknowledgement information comprises synchronization information used to indicate time synchronization between the source base station and the target base station, the synchronization information comprises the target preamble which is a unique preamble in the target root sequence, used to uniquely identify time synchronization, in a same root sequence, the synchronization information is further used to instruct the source base station to send a handover command to user equipment, UE, and the handover command comprises the target preamble.