Abstract: In traditional Fourier transform profilometry, the astigmatism projection is used and 4 constraints are needed to obtain accurate mapping relationship between phase and height. Moreover, the phase nonlinear quadratic error caused by astigmatic projection can also reduce the topographic recovery accuracy. In order to reduce the influence of phase nonlinearity in less restricted conditions, a universal model based on parallel optical interference projection was established. The reference plane phase under the parallel optical interference projection changes linearly along x-axis, the phase distribution is more accurate than the astigmatic projection or oblique projection. The restoration of the measured object under astigmatism and parallel light projection was compared and analyzed. The experimental results show that the new model has high flexibility and operability under less restricted conditions, and the recovery accuracy is good, the relative error is 1.1%.