The precise opto-mechanical analysis plays a key role in optimization design of the system.In actual conditions, the optical components of opto-mechanical system may have asymmetric changes due to the effect of coupled fields.To solve the problem, a 3D interface model based on Zernike polynomials fitting was built to improve the data transferring precision of opto-mechanical analysis.Thus the high-precision analysis under coupled fields was realized.To make an optimization design of a certain opto-mechanical system, we made an integrated analysis of the gravity field and the temperature field, extracted the asymmetric distrubution of optical surface changes, and made an analysis to the imaging quality of the system by using the 3D interface model.The results indicate that the interface model can be used in the actual condition of coupled fields for opto-mechanical analysis.