This paper discusses the gray fuzzy evaluation method about the performance of ERP system. The index system is classified based on the balanced scorecard method, and which largely shows the main factors influencing of ERP system performance. According to the mathematical model, the quantitative process of gray evaluation is given and examples are calculated. Basically has the following conclusion, gray fuzzy comprehensive evaluation method can not only make full use of each evaluation index about financial, customer, internal processes and learning information, but also can be used to describe the level of performance, transverse comparison. This method has a wide range of practicality and good maneuverability, and the performance evaluation of ERP system has reference value.