The self-collimation of two polarization statcs of electromagnetic waves in two dimensional photonic crystals is studied by using finite-difference-time-domain(FDTD) method.It is proved that self-collimation can be realized in both transverse electric (TE) field and transverse magnetic (TM) field simultaneously by modification of the appropriate photonic crystal structures.Analysis and numerical simulation were carried out.This effect may be important for creating integrated optical circuits,and for improving the efficiency of light source.