1. A method for establishing contact relationship of online user accounts in a network communication system, the method comprising: selecting, by a server of the network communication system, at least two target users from contacts of an introducer according to a selecting instruction initiated from a contact selecting interface displayed on a first user terminal of the introducer, the server and the first user terminal each comprising at least a processor; sending, by the server, an introducing request to respective user accounts of the selected target users, wherein the introducing request is presented as a system message on respective second user terminals of the selected target users, the presented system message including a list of common contacts associated with the respective user accounts of the selected target users, the presented system message further including information of the introducer, of another of the respective user accounts of the selected target users, and a clickable option to accept or decline, such that the presented system message is sufficient enough to enable accepting or declining so as to increase efficiency in establishing contact relationship; monitoring, by the server, response instructions from the respective user accounts of the selected target users; after detecting that the respective user accounts of all the selected target users return response instruction for accepting the introducing request: generating, by the server, contact relationship data between the respective user accounts of the selected target users; and sending, by the server, information indicating that the introducing process succeeds to a user account of the introducer, wherein the information indicating that the introducing process succeeds at least comprises names of the selected target users, and prompt information indicating that the introducing process succeeds; and after detecting that at least one of the user account accounts of the selected target users returns a response instruction for declining the introducing request: sending information indicating that the introducing process fails to the user account of the introducer, wherein the information indicating that the introducing process fails at least comprises: the names of the selected target users, reason information showing why the introducing process fails, an information inputting box for the introducer to input reasons for introducing, and a trigger for sending content received by the information inputting box to the at least one of the user accounts that has declined the introducing request.