Air layer with irregular shape in sound absorbing structure is formed by different structure mode of materials. With building multiform interior space by materials and structure mode, it makes the shape of air layer between the facing and the structure of building to be irregular shape.According to related study of absorbing structure, it shows less information about the influence of air layer with irregular shape. The factors of sound absorption of absorbing structure were focused on absorbing structure which facing paralleled structure of building in past research. For searching the influence of sound absorption of absorbing structure caused by the air layer with irregular shape, the subject in this study is set as the air layer with irregular shape which facing tilts with single-axis. The factors of air layer with irregular shape are the angle between tilting facing and horizontal face, the length of span of tilting facing, and if the setting is that the air layer is divided into several parts not to be interlinked. By these factors the sound absorption characteristics of air layer with irregular shape are shown.In the other point of effects of absorption coefficient causing by setting of air cavity, both panel and perforated panel structure the influences are influenced mainly at low frequency, especially at 200 Hz. Whether the air cavity is set or not, the panel structure reveals less influences and the absorption coefficient reduces as increasing of span at low frequencies.