In order to warn and prevent haze effectively, an regional haze warning system for heterogeneous networks is designed in this study. The system consists of collection module, coordinator, gateway, server, and display terminal. It collects sensor data by deploying three kinds of heterogeneous networks, i.e., LoRa, NB-IoT, and ZigBee. The gateway is designed to achieve data uploading. As the brain of the whole system, the server achieves the classification pre-warning by providing analysis and processing of the environmental information, triggers the corresponding mechanism response, and takes corresponding measures. Firstly, this paper introduces the overall design of the system and the working mechanism of the classification pre-warning. Then, the classification pre-warning mechanism is improved by the support vector regression model which is optimized by genetic algorithm. Finally, the system is proved to forecast haze stably and effectively by analysis of the case.