Properties of photonic band-gap in one-dimensional multicomponent photonic crystal were studied by optical transfer matrix method. We mainly analyze the relations of photonic band-gap property with the arrangement,refractive index and geometrical thickness of components. Then the filtering properties of a photonic crystal narrow band optical filter were investigatel,which is made of two pieces of one-dimensional multicomponent photonic crystals with different photonic band-gap due to the different arrangement of components.