By introducing ES (Expert System) of AI (Artificial Intelligence) and KP (Knowledge Processing), etc. into DSS (Decision Support system), the study on design of IDSS_EER (Intelligent Decision Support System of Engineering Equipment Repair) is discussed in detail combined with the characteristics of EER (Engineering Equipment Repair).To start with, the research status quo and analysis of IDSS problems are analyzed and the traditional design problem of IDSS is improved in the system structure and system function of IDSS with a clear aim. Finally, the design and development of IDSS_EER are given a particular description. The system design embodies the strong points of the qualitative and quantitative analyses and can be achieved theatrically and technically. Simultaneously, the system provides the man-in-the-loop support and avoids the intelligent blindness.