It is an important direction that introducing Distributed Expert System into Decision Support System to form Intelligent Decision Support System in this research field. But Current resolutions does almost not involve in the heterogeneity of Expert System all. For this, the objective of this paper is to study the organizational pattern between Distributed Expert System and Decision Support System, and design an Intelligent Decision Support System supported by heterogeneous Distributed Expert System. Firstly, a unified descriptive method of heterogeneous knowledge is presented. And then, an architecture integrating heterogeneous Distributed Expert System and Decision Support System is provided. Finally, a hierarchical approach to cooperate and manage Expert Systems have different degrees of capability is given. The result of analysis shows that the architecture given in the paper can improve the scope and precision of Intelligent Decision Support System to resolve problems.