By the characteristic matrix methods,the rule about reflectivity changing with the incident angle of the TE wave and the TE wave in the photonic crystal whose refractive index is discontinuous to change with the sinusoidal function is studied. The main forbidden bands of the TE wave and the TM wave contain same characteristics,the scope of the incident angle of the main forbidden band is all small,in 0～0.11 rad. The bigger the amplitude of refractive index and the period number are,the better the quality of the main forbidden band is. There is no “general Brewster's angle”phenomenon in the reflected wave.