Abstract: In order to reduce sideband spectral energy and improve image lining of a quartz filter,a novel filter structure was designed and its characteristics were analyzed theoretically. Taking a three-level quartz filter for example, its sideband energy can be reduced efficiently by adding the same structure as the first or second level after the third level. Comparatively speaking,it is better to add a structure the same as the second level. The outcome provides academic gist to reduce sideband energy in spectral observation.