S Transform combines the advantages of the windowed Fourier transform and the wavelet transform. It is a kind of nondestructive and reversible time-frequency analysis method for the non-stationary signals with the characteristics of the linearity, multi-resolution and the only one inverse transformation existing. In addition, it has direct relationship with Fourier transform. Due to the shortage of the phase description based on the 1st-order Taylor expansion in the S transform “ridge” method, a more accuracy phase expression based on the 2nd-order Taylor expansion is proposed. According to the strictly theoretical analysis, a more accuracy calculation expression formula of the phase field is gotten and corresponding computer simulation and experiment are finished, which enriches the theory of S transform and improves the measurement accuracy of S transform. The three-dimensional (3D) reconstruction results based on the 1st-order Taylor expansion are also compared with that based on our method in S transform “ridge” method. The simulations and experiments show that the reconstruction of the surface from the 2nd-order Taylor expansion has higher measurement precision.