Abstract: A new method in designing narrowband spectral high-reflectivity filters is proposed.The filter utilizes optical characteristics of a metallic film material that has a property of n k a symmetrical F-P filter,and a film of Ag.The narrowband spectral high-reflectivity filter structure is given in the visible spectrum.A few of the formulas of itS spectral reflection property,such as the reflectivity,maximum reflectivity and refltalvity-bandwidth,are derived and proved by experiment.In the mean-time,a method of designing narmwband spectral high-reflectivity filter in the non-visible spectrum is also proposed.