The invention discloses a structural damage identification method based on ridge estimation and an L curve method. The structural damage identification method comprises the steps of firstly, building a structural damage equation based on sensitivity of modal strain energy according to the sensitivity of the structural modal strain energy, then determining a basic estimation criterion of the ridge estimation according to the principle of Tikhonov regularization, then utilizing the L curve method for determining the optimal ridge parameter of the ridge estimation, working out the basic solution of the structural damage equation on the basis of the optimal ridge parameter, and finally correcting the result, so that the damage coefficient of a damage unit is obtained, and the structural damage is identified. According to the structural damage identification method based on the ridge estimation and the L curve method, by the adoption of the ridge estimation, the influence of an ill-conditioned problem on damage identification can be greatly reduced, the quasi-optimal ridge parameter is determined by the adoption of the L curve method, meanwhile, a correcting strategy for the ridge estimation is provided, and therefore the better damage estimation value is obtained.