The invention discloses a network security situation perception system and a method based on multilevel multi-angle analysis, wherein the system comprises a data gathering module, a network security situation understanding module, a network security situation estimation module and a network security situation forecasting module. The method for achieving the network security situation perception system comprises the following steps: firstly, doing statistical data fusion and association analysis to data in the aspects of assets, intimidation and vulnerability of a network system gathered by a sensor, and getting normalized data, secondly, analyzing the normalized data after the fusion of the step one, and doing network security situation special subject estimation, thirdly, doing network security situation factor estimation according to the normalized data obtained in the step one and the estimation result of the step two, fourthly, doing the integral estimation of network security situation according to the estimation result of the step three, fifthly, doing network security situation forecast according to the estimation result of the step D. The invention analyzes the security situation of network from multi levels and multi angles, and guarantees a result perception system to be more accurate and comprehensive.