The tooth flank region that reflects the tooth flank shape information in the interferogram is surrounded by background noise, and its processing accuracy has a great impact on the subsequent processing steps such as phase unwrapping and the interferogram registration, which is directly related to the accuracy of the final measurement result. Aiming at the phenomenon that there are spurious fringes in the boundary of tooth flank interferogram, a tooth flank region segmentation method combining Butterworth filter and Haar wavelet is proposed by analyzing the distribution of tooth flank interferogram fringes. Finally, under the experimental conditions of this paper, it shows that the proposed method can exclude and correct the wrong phase values of the unwrapping in the boundary spurious fringe regions of the tooth flank interferogram from the valid measuring region by comparing with the time-domain segmentation method, which proves that the method based on the frequency domain can effectively improve the accuracy of the segmentation of the tooth flank region of the interferogram.