The calibration of phase-height mapping system plays a decisive role in the accuracy of three-dimensional reconstruction and detection of phase measurement profilometry. The influence of fitting order on the calibration accuracy of phase-height mapping system based on polynomial fitting is mainly studied. Through the calibration of one to six orders polynomial fitting and three-dimensional height reconstruction, it is found that the fitting height of one to four orders can achieve a good height reconstruction accuracy, and the absolute error Δ is less than 5 μm.The polynomial fitting calibration coefficients of one to four orders are further studied and analyzed. It is found that when the fitting order is two, it has higher reconstruction accuracy and stability, and the absolute error Δ is 1.36 μm the relative error δ is 1.34% and the standard deviation is 0.262.