Abstract: Definition and construction of the entity relation in a new computer aided urban planning system named CAUPS were implemented to solve problems of weak data exchange ability,non-cooperation between systems and low efficiency in the current computer aided urban planning system.A knowledge query and manipulation language(KQML) based message format was used for communication between entity agents,and rules in the knowledge database were also presented by the KQML technique.Evaluation models can be customized to meet user' need using the entity relation.Two kinds of attribute adjustment strategies,lightweight synchronization control strategy and heavyweight synchronization control strategy,were proposed to realize synchronization,harmony and control between agents.The entity relation customization based implementation method of evaluation models and the cooperation strategies between agents were successfully applied to the planning project of the region along Qiantang River of Hangzhou.