Typical WSN (Wireless Sensor Network) applications in precision agriculture include production process management, plant growth optimization, farmland monitoring and so on. Middleware, which can connect hardware, applications, and enterprise systems, is required to construct ubiquitous agricultural environment combining WSN technology with different agricultural applications, but there have been insufficient studies in the field of agricultural-oriented WSN middleware compared to other industries. This paper proposes a middleware to process data collected from agricultural environment by applying WSN technology, analyzes the data and standardizes different data forms, and provides intelligent diagnosis service and event service. One of the advantages of the proposed middleware is to build a model library which will guide the agriculture production process, such as irrigation control and disease prevention. In addition, a web-based remote login is provided to all users around the world to browse agricultural environmental parameters and to reference for intelligent decision.