Liao River Basin Water Environmental Management System is wide in geographic distribution. It has multi-level, provincial and municipal districts of data between nodes need to transmit and exchange. Liao River Basin Water Environmental Management Information System is involved in many departments. The multi-node need data transmission and exchange. In order to solve such a large system of complex exchange, design and implement the domain model. The overall structure of the model of domain and each element is discussed, and the key module-domain identification module, trust models and cross-domain communication is introduced emphatically.