For the configuration damage discrimination of JJ160/41-K oil derrick, this article advances two-step means based on mode parameters and SVM: Firstly based on flexility matrix, damage location of derrick is discriminated; and then, regarding flexility curvature difference as discrimination index, a quantitative analysis on known-damage-location derrick is done with splendid regression of SVM . Simulation Results indicates this method can analyse damage location and degree of derrick structures effectively.