Photonic crystals (PCs) can be divided into simple PCs and compound PCs. Laser holographic interferometry is one of the important methods in the fabrication of compound PCs, in which beam polarization plays an important role. By using a four-beam configuration with certain symmetry to produce compound PCs, numerical simulations are conducted using Matlab programming to systematically study the influence of various polarization combinations (including single-beam, double-beam, three-beam, and four-beam cases) on the unitcell shape and interference contrast of the compound PCs. The research results show that the polarization degree and rotation angle of each beam have a significant effect on the compound PCs. Under different polarization conditions, a series of rich unitcell shapes, such as wavy stripes, elliptical cylinders, zigzags, are obtained. In addition, it is found that when all the interference beams are linearly polarized, the compound PCs have the optimal contrast. The results obtained in this work have certain theoretical guidance significance for the experimental fabrication of compound PCs with various unitcell shapes, as well as the development of virtual experimental research.