The transmission spectra of 1-D photonic crystal of periodic positive-negative index structure at angular incidence was studied by transfer matrix method. The results show that the photonic band gap structure changes along with the change of incidence angle,especially for the dispersive 1-D photonic crystal composed of positve and negative refractive index materials,a new type of photonic band gap corresponding to zero of negative refractive index arises,of which the center is invariant upon the change of incidence angle,but the width broadens when the incidence angle increase;likewise,for a Bragg gap,the center and width of band gap change,which make the condition of achieving complete phase matching for the second harmonic effect.