An improved model of curvature modal recognition is proposed to solve the problem that the curvature modal cannot recognize the damage of the tip and root of the structures. Blade-disc is one of the most important components of the aero-engine structure, and if it fails, it will cause a serious threat to the safe operation of the engine. The curvature modal method which is strongly sensitive to the structural faults is used to compare the changes of the blade-disc modal from different damage locations and different damage degrees, and the structure end is calculated by using the improved curvature modal method. The numerical results show that when the blade-disc is damaged, the displacement mode and structure frequency are difficult to reflect the damage position of the structure effectively, and the natural frequencies of each order mode will get decreased; the curvature modal method which can reflect the damage condition of the structure effectively gives a qualitative description of the damage degree, and the curvature changes abruptly at the damage place; the improved curvature modal recognition model can identify the damage fault at the end of the structure, which provides a theoretical basis for damage detection of aero-engine blade-disc structures.