Abstract: Phase shift error is the main source of phase measurement error in phase measuring profilometry(PMP). A method of measuring the accurate phase shift and eliminating the phase measurement error caused by phase shift error is proposed. The step phase shift between two frames can be calculated by using FFT based on the principle of Fourior transform profilometry (FTP). When the accurate phase shift is obtained, accurate phase measurement can be accomplished using only three frames. Thus, the error caused by phase shift inaccuracy is eliminated and the system measurement accuracy is improved. Simulations and experiment are carried out to verify its effectiveness. The results show that the method can accurately measure the phase shift and improve phase measurement accuracy.