The finite-difference time-domain (FDTD) method is developed for the study of transmission characteristics of 2-D photonic crystals. Transmitted power of TM mode and TE mode of 2-D square lattice photonic crystals are given. Based on scaling properties of photonic crystals, the photonic crystal behaving in the electromagnetic zones is fabricated and experimentation is designed. The theoretical results confirmed the experimental results. It is shown that the light with a certain frequency and incident direction can not propagate in the photonic crystal.