In this paper, we give the expressions of transmissivity, reflectivity and the distribution of election field in a photon crystal at an arbitrary incidence angle. We investigate the field intensity when angle frequency of incidence light is odd or even times the fundamental frequency in photon crystal. Besides, we study the effects of incidence angle, the incident direction of light and defect layer on election field distribution, and obtain some new and valuable results. We expect the research results to be helpful for designing photonic crystals.