By the equi-frequency contour analysis and the finite-difference time-domain simulation, it is observed that the distance of one lop in a photonic crystal self-collimation ring resonator can cause different periodic outputs of the ring resonator for TE and TM polarizations. Equal intensity polarization-independent beam splitter can be achieved by choosing a suitable propagation distance. It expands the range of application of beam splitter and will play a great role in integrated optical circuits.