Acousto-optic tunable filter (AOTF) is one of important optical switch components in optical networks. The possibility of tellurium dioxide acousto-optic tunable filter (TeO2 AOTF) as an optical add/drop multiplexer (OADM) is studied on the basis of the theory of the anomalous acousto-optic Bragg diffraction and the design principle of non-collinear AOTF. Its main performances and structure are analyzed and discussed, and the significance of incident angles and interaction lengths for its performances is presented. The model for optimization design is built under some limitation and the transducer areas is adopted as a regulator for performance, the designed example of the TeO2 AOTF for WDM systems is given by the optimized method.