Wavefront aberration is an essential factor that significantly affects the image quality of an optical system. We proposed a comprehensive method to determine the wavefront aberration of a deformed optical component caused by clamping forces. First, the displacement of the elements on the optical component, induced by external forces, is calculated using ANSYS software. Then, the deformation surface is fitted with an aspherical surface to obtain Zernike coefficients. Finally, the wavefront aberration is obtained from Zemax using the Zernike coefficients and the parameters of the optical component. An experimental study on a spherical mirror is carried out to verify the accuracy of this method. A Zygo interferometer is used to measure the actual wavefront aberration of the deformed mirror. The result indicates a good agreement between the theoretical calculation and the experimental data, with a variation of <10 % for various applied forces. Our finding provides a meaningful and reliable method for designing and selecting reasonable mounting structures to ensure the image quality of an optical system.