The region segmentation is an important pre-processing step in optical interferogram processing, in which the effective region is extracted from interferogram. The region segmentation of interferogram widely exists in the experimental testing and data processing of various digital wavefront interferometers. It has important influence on accurate wavefront retrieval and reliable implementation of phase unwrapping. The paper introduces the region segmentation technology of three kinds of popular interferogram, including single-frame interferogram, simultaneous phase-shifting interferogram and lateral shearing interferogram. The related research progress is systematically summarized, and the research trend in this field is also prospected.