Wireless Sensor Network(WSN) is widely used in Emergency Management System(EMS) to assure high safety. Real-timely transmitting emergency information in dynamically changing environment should be assured in mission critical district. Conventional methods based on static situations and centralized approaches can not satisfy this requirement. In this paper, to assure real-time property, autonomous community construction technology is proposed to set special area called community which includes a special passage composed of several routers for emergency information's transmission and routers around this passage in one hop range. Emergency information's transmission is protected by routers around this passage from interference of other sensing information's transmission in and outside community. Moreover, autonomous community reconstruction technology is proposed to guarantee real-time property at failure conditions. In this technology, community members autonomously cooperate and coordinate with each other to setup a bypass in community for transmitting emergency information if fault happens. Evaluation results indicate effectiveness of proposed technology.