The electro-mechanical impedance method identified as a suitable method for structural health monitoring and damage detection in structures, which is considered as a non-destructive inspection method. Piezoelectric smart materials are used as sensor/actuator to excite the structure and is installed on the structure, which has the task of identifying and measuring any changes in the structure. The basis of the electro-mechanical impedance method is to identify the detections due to the change in the stiffness of the structure, and it depends on geometry and properties of the materials to be studied. Detecting the defects that created on frame structure (L-shaped beam) by electro-mechanical impedance method and validation the analytical method by comparison with the experimental method is this paper’s objective. Defects are created in the groove shape before and after the bend and the real impedance spectrum of damaged frame that obtained from the experimental method at each step compared with healthy frame, and the damage index figure have been extracted. Also, the real spectrum of the impedance obtained from the experimental tests will be compared with the real spectrum of the impedance that obtained from analytic method. Comparison of the impedance spectrum and also the damage indexes from experimental tests for a healthy structures and defective structures shows compliance between the Stiffness and impedance of structure. Also the spectrum of real part of impedance obtained from the analytical method for the frame structure in the case of a cantilever boundary conditions has a correlation with the experimental tests.