This paper introduces the design method and testing results of a dual-band acousto-optic tunable filter with large aperture angle. This tunable filter has the function of simultaneously filtering out visible light and mid-waves, its high-frequency band is responsible for filtering out visible light (450-750 nm), and the low-frequency band is responsible for filtering out mid-waves (3 000-4 500 nm). This filter employs tellurium dioxide crystals as the acousto-optic medium material, with an incident angle of 20°, an ultrasonic angle of 98.55° for the visible light band, and an ultrasonic angle of 99.65° for the mid-wave band. When the interaction lengths are 3 mm for the visible wave band and 23.1 mm for the mid-wave band, both the visible light and mid-wave bands achieve an aperture angle of greater than 6°.