Abstract: According to matrix perturbation theory, the structure mass and stiffness matrixes were expressed as functions of element damage parameters, and a new method for structure damage detection based on the perturbations of frequency and mode shapes was proposed. First, according to the changes of mode shapes between damaged and undamaged structures, damage pre-determination and determination equations were established. The perturbation of mode shapes were used to solve element damage parameters, when the damage extent of the same element solved from pre-determination equations were agreed with the one solved from determination equations on the whole, the element was damaged. Then the detection results were substituted into damage check equations based on frequency difference to check the precision. The damage detection equations established from this method were a statically indeterminate problem which can guarantee the uniqueness of recognition results, avoid ‘pseudo damage’ phenomenon. Numerical examples show that even the structure were multiple and low extent damaged，only one-order mode was needed to identify the damage. Furthermore, when the extent of damage is small, the first-order perturbation equation could be adopted; while the extent is large, the second-order perturbation equation could be employed to improve the precision of the identification result.