A method for maintaining uplink synchronization in P2P (Peer to Peer) communication, performed by a user equipment in wireless communication systems, comprising: negotiating with a wireless communication network system about the schedule and parameters for controlling the uplink synchronization of the user equipment by the procedure of establishing P2P direct link; transmitting testing signals to the network system via a customized uplink channel according to the negotiated parameters; receiving the control information transmitted via a customized downlink channel from the network system according to the negotiated schedule; and maintaining uplink synchronization of the user equipment in P2P communication according to the control information. Uplink synchronization can be realized through the customized channel, so the present invention can overcome the problem of overload brought by implementing uplink synchronization through the downlink common control channel and system performance degradation caused by increasing the transmitting power of the user equipment to transmit P2P signals.