Recently, Wireless Sensor Network(WSN) technology has been used in various fields, which provides a wide range of surveillance and monitoring applications convenient. Applying WSN technology to fire alarm of large buildings can not only help the earlier detection of fire hidden trouble ahead of time, but also give us instant and reliable information in fire fighting process. Based on the hierarchical structure of WSN, this paper build a fire detection framework for large buildings. As for the lower layer of the framework, we use CC2430 added some sensors to be the sensor node, and the middle layer using Zig Bee technology to turn the isolated sensor nodes into a wireless network, while the upper layer using B/S type by building the JSP pages to show the surveillance center about some meritorious environmental parameter, locations of fire, other situation of the building and so on. By this way, it can be more humane for the monitoring of information, and provide a choice for the application and promotion of WSN in other areas.