Based on the multiple beam interference principle, the common rules and influence factors in holographic fabrication of photonic crystals are studied. Furthermore, taking triangular lattice as an example, the polarization combinations influence on photonic crystal microstructures is studied by Matlab simulations. Using symmetry of the beam configuration of triangular lattice, the influence of polarization combinations on the intensity maximum, minimum value and contrast under the equal intensity condition is studied by dividing ten kinds of polarization combinations into three groups. The influence rules of polarization change on the photonic crystal microstructures are further summarized. Finally, a set of optimal polarization combination for triangular lattice with optimal contrast is obtained.