Based on the transmission matrix method， the reflection spectrum of TiO2-SiO2 photonic crystal has been simulated by the MATLAB software.Under the conditions of the optical thickness of the medium meeting the1 /4 film， the influences of incident angle，dielectric thickness and the number of cycle on the band gap are discussed.It is found that the modulation of photonic band gap can be realized by changing the incident angle， the dielectric thickness and the number of cycle.