In order to inversed compute the optical element surface profile using the finite element method and the surface shape interference test results, the composition of interference test results was decomposed, and the testing principles of the rotational averaging method were analysised. The feasibility of using simplified geometrical model to caculate the deformation of an optical element with arbitrary given surface shape was discussed. Surface profile inversion model was proposed based on finite element method. A finite element analysis model was then presented based on surface-surface contact modeling. A plane mirror supported by three rigid spheres as the simulation and experimental model, the rotationally asymmetrical surface deviation was quantitative analysis using the numerical method presented in this paper and the N-step rotational averaging method. The obtained results show that the root mean square of rotationally asymmetric surface is 2.933 nm obtained through numerical method and the root mean square of rotationally asymmetric surface is 2.75 nm obtained through N-step rotational averaging method. Subtracted result of the two rotationally saymmetric surface show that the root mean square of the subtraction are 6.31% of the numerical method result and 6.73% of the N-step rotational averaging method result. Finally, comparing the optical element surface profile computed by proposed inversion model with the surface profile tested by N-step rotational averaging method. Results show that the root mean square of optical element surface profile are 3.535 nm and 3.351 nm respectively. Subtracted result of the two surface profile show that the root mean square of the subtraction are 11.67% of the inversiong result and 11.06% of the result tested by N-step rotational averaging method .The proposed inversion model is accurate and reliable.