Abstract: To solve the problem of human subjectivity in the process of classification of system, an approach of information system grading based on gray-fuzzy comprehensive theory and information entropy was proposed. Firstly, a gray-sample matrix of grading indexes was constructed and a gray-evaluation matrix was obtained by gray-fuzzy theory. Then, the weights of grading indexes were calculated by information entropy and the severity of object damage was determined. Finally, the grading of information system by combing the matrix method was obtained. An illustrative instance of the subsystem of the enterprise information system was given to demonstrate the general process of information system grading. Results show that the damage degree of subsystem object is 2.379 and the protection classification is determined as the grade-Ⅲ. The experimental analysis proves that the proposed grading method can determine effectively the level of information system. Meanwhile, it acts as a subsidiary of traditional qualitative method.