Abstract: There is great difficulty in solving systematic electronic equipment testing assessment for reductionism. Taking the typical integrative command information system for example, the information transmission process is analyzed based on the OODA loop theory, and the essential connotation of the command information system is also derived. From the perspective of complex system, the complexity of the integrative command information system is studied. Through analyzing the complexity with the unique traits of the integrative command information system, it can be concluded that there is essential difficulty of problem decomposition by custom performance testing method in systematic electronic equipment test, and the reason is that the performance testing method conforms to reductionism. To solve this difficulty, a methodology for problem decomposition is put forward based on systematology meta-synthesis method, and it is used in command and control system test assessment. An example of constructing anti-interference indexes system is given for the integrative air defense command information system. The example has illustrated the application process of the decomposition method and demonstrated that the method is of great value in effectiveness evaluation of system of systems combat test for electronic information equipment.