In order to detect the damage locations of the cantilever beam with multiple damages, modal analysis based on the large commercial finite element software ABAQUS and modal experiment test method were adopted by using modal strain energy method. The low-order modal strain energy before and after damage of a cantilever beam structure was obtained, and the strain energy difference was used as damage index to identify the damage. The simulation and experimental results showed that the modal strain energy can be used to locate the damages of the cantilever beam. Based on the validation of the effectiveness of the method, the influencing factors of the beam structure damage detection were analyzed, including the arrangement of measuring points, the number of sensors, the position of sensors and the number of modal order. The result demonstrated that: 1) The damage location of the beam with multiple damages can be detected by the first three order of modals, and the locating effect is the ideal when the distance between the measuring points is roughly equal to the width of the beam;and 2) The number of sensors has no obvious effect on the damage detection and localization.