The invention discloses a large-scale fire alarm monitoring system having a simple structure. The system is composed of a node device, a data communication module, and a host device. The node device is used for collecting data and identifying and processing the collected data. The data communication module in communication connection with the node device is controlled by the node device and is used for sending and receiving data from the node device. The host device consisting of a CPU processor and a 3G module is in communication connection with the data communication module and is used for controlling data transmission and receiving of the data communication module3 and processing the data. With the data communication module for data communication, the communication distance between points is increased; the construction restriction on the flame monitoring point by the large-range monitoring fire monitoring area with the complex topography is eliminated; and the accuracy and stabilityof a large-range fire monitoring system are improved substantially.