Abstract: Structure Damage Detection Method(SDDM)based on frequency measurement exhibits a feature that natural frequencies of a structure can be measured conveniently with relatively high precision. Some improvements to the SDDM proposed by Stubbs are presented. Simulation analysis for a 3-span continuous RC beam is given. For slight and moderate damage detection, the results are satisfactory. It is shown that the proposed algorithm has the advantages of computational simplicity and better identification capacity. Therefore, it is convenient for engineering practice.