The invention discloses an adjacent communication service realizing method and device, and relates to the communication technology. In the UE contact signing process, an adjacent communication service identifier is assigned for the UE, so that after an adjacent communication service request sent by the UE is received, the adjacent communication service identifier of the UE is determined, and then adjacent communication service is realized according to the adjacent communication service identifier of the UE, so that the condition that the adjacent communication service cannot be performed because a network cannot determine the 3GPP network internal identifier of the UE according to the application identifier of a user can be avoided, so the adjacent communication service of the UE can be realized.