This study is aimed to establish a wireless sensor network (WSN) gateway model prior to the back-end server for diverse environmental monitoring applications. The design catalogs different sensor data with transmission load balance to incorporate heterogeneity of sensor signals, stability of data transportation, and expenditure of mobile communication. As considering a variety of sensor characteristics for environmental monitoring, the proposed WSN gateway is designed with three bridged functions, including serial listener, transaction logger and Internet listener, to enable analog and digital signal conversion, physical data classification, threshold determination, database redundancy and mobile communication. The criterion-based scheme is created for remotely updating thresholds of monitored data from the back-end server to the gateway. The model is built upon the embedded computer for low power consuming to perform efficient and stable applications. The comprehensive model design can be easily utilized for general WSN surveillance with expansibility and flexibility.