During the rating of network security situation problems, the traditional methods treat the network security threat rating and ranking assessment as the same problem and the assessed values are transferable. In order to solve the problem, the forming mechanism and rating of the network security threat problem is introduced. The membership functions of the indexes of network security rating are structured and the indexes weights are determined using cross entropy and entropy. Then, the fuzzy comprehensive evaluation model based on variable weight is proposed, further, the grade assessment of network security threat situation are computed using two-tuple semantic method. Finally, the new ecological retail enterprises of network security threat rating are taken as an example and the analysis results also given. It was illustrated with a real example that the fuzzy comprehensive model and method of the grade assessment of network security situation are more operational, intuitionistic and easily explained, which better reflects the character of network security situation and provides a new way for network security situation rating.