Polarization cameras integrated with conventional four-channel micro-polarization arrays (MPA) are usually used as phase shift devices in focal plane-type interferometric systems to achieve simultaneous phase shifts. However, such phase shift devices suffer from low sampling rates and a lack of mature resolution reconstruction techniques to resolve pixel-level alignment errors. To solve such problems and further improve the phase reconstruction accuracy of the focal plane interferometric system, this paper proposes to apply the "Bayer-like" three-channel MPA to the interferometric system to realize the simultaneous phase shift. The arrangement of the three-channel MPA can reduce the processing complexity of the element and improve the inter-channel sampling rate. In addition, this structure can better utilize the resolution reconstruction idea of color filter array (CFA) to solve the inherent pixel-level alignment error problem between simultaneous phase shift interferograms. Taking lateral shearing interferometry as an example, the process of acquiring simultaneous phase-shifted interferograms and phase reconstruction in an interferometric system with threechannel MPA is verified by simulation. The experiment results shows that the proposed three-channel MPA structure performs better than the traditional four-channel MPA structure in terms of visual reconstruction effect and quantitative index of phase reconstruction.