Objective To investigate the effect of the cirrhosis and detachment of the ligaments, tendons and stapes replacement prosthesis on the sound transmission of the human ear. Method Based on the CT data, the geometrical model of human ear is established by a C++ program developed by the authors. Then numerical model is built up through the finite element software PATRAN where the geometrical model is imported and the material properties, interface of the joints and boundary conditions is defined. Result Amplitude variation laws of the stapes footplate and umbo are obtained by comparing the frequency response analytic results between the normal ear and pathological ear, Moreover, the sheath shaped stapes replacement prosthesis is constructed based on the analysis of the numerical model developed by the authors. Conclusion The accuracy of the model in this paper has been validated by the well matched computational and experimental results in normal ear, and it can be used to simulate the human transmission. The computational results of pathological ear can explain the effect of lesion for sound conduction from the mechanical view, and provide a reference for the treatment of ear illness. Comparing with the effect of the ring shaped stapes prosthesis which is commonly used in our country, the sheath shaped stapes replacement prosthesis is more suitable for the physiological function of the human ear and the hearing recovering effect will be better.