This paper mainly deals with a model of comprehensive evaluation based on interval-valued fuzzy mathematics.In the model the evaluation index system has been built according to the physical security, logical security and management security of network system.In order to determine the weight vectors, the membership frequency intervals, the intermediate values and the frequent number of each intermediate value have been defined.Then on the basis of the fixed weight vectors and actual situation, giving the fuzzy evaluation vectors, all the scores of index levels can be valued.This method not only makes evaluation results more in line with objective facts because it combines the objective weight with subjective experience to avoid the subjectivity of previous evaluation, but also makes network and information security evaluation easily on computer.