Temporary discussion groups and the coordinates of the personnel need to be quickly established in such indoor situations as temporary meetings, so as to carry out point-to-point discussion on the purpose of relevant personnel. This study designs and implements instant messaging system based on indoor positioning system. The system is mainly divided into indoor positioning module and instant communication module, and it has realized the functions of group chat in LAN, searching people, and communicating with people nearby. The system is simple in structure and easy to implement. This system is applicable to seminars, product promotion, and other scenarioss. The system has a solid application prospect.