A frequency change-based structure damage positioning and damage degree evaluating method is characterized by comprising the following steps: establishing a finite element model of a non-damage structure as a reference finite element model; carrying out vibration test on a damage structure, and recognizing m-order modal frequency of the damage structure; carrying out damage degree evaluation on the damage structure; and confirming the damaged position of the damage structure. The method can accurately position the damage and evaluate the damage degree only by utilizing finite low-order frequency information before and after the damage of the structure without the need of structure vibration mode information, and is applicable to single damage and multiple damage working conditions, thus having certain practical application values.