The invention discloses a backbone net rack survivability assessment method based on LDA and PCA. The method comprises the steps as follows: firstly, specific characteristics of a backbone net rack are planned according to differentiation, and a backbone net rack survivability assessment index system is constructed; then, on the basis of the constructed backbone net rack survivability assessment index system, a second level index attribute valve is obtained by using an LDA backbone net rack survivability assessment third level index, a first level index attribute value is obtained by using a PCA backbone net rack survivability assessment second level index, and a backbone net rack survivability assessment result can be obtained according to the first level index attribute value. The method solves the survivability crossing problem of an inter-class backbone net rack scheme and provides a theoretical basis for optimum survivability assessment of the multi-scheme backbone net rack with classified information.