Based on the analysis of the campus network system risk and its impact factors of a university, we evaluated seven major risk factors of campus network systems with the improved risk matrix method, and built the risk matrix used in the risk assessment of campus network system, designed the basic procedure of the risk assessment with the risk matrix, in order to provide a scientific, reasonable and effective evaluation method to the risk assessment of this campus network systems. An example application shows the result of this method is more reasonable and the evaluation is more objective compared to traditional methods.