With the continuous development, computer technology promotes the rapid development of science, and the Internet of things (hereinafter referred to as IOT) technology is the product of the rapid development of science and technology. With the increasing popularity of IOT technology, modern technology has been gradually applied to various fields. Building intelligent system has also begun to apply IOT technology, which has become an important area of building intelligent system. A complete intelligent building system is composed of many different networks, which requires IOT technology to play an important role. Building intelligent system construction needs to rely on a variety of technologies, such as network system, information system, lighting system and security defense system, which will achieve various functional systems. Therefore, IOT technology can not only achieve the goal of unattended, but also reduce the cost of building management. Through IOT technology, we promote the communication between things and people. Firstly, this paper analyzes IOT technology. Finally, this paper lists the application of IOT technology in intelligent building system