As for the common acousto-optic tunable filter (AOTF), the optical wavelength is directly tuned by the frequency of the applied radio frequency (RF) signal. The working wavelength range of the RF controlled AOTF could be limited by the performance of the RF source, especially in the high frequency area. We have proposed a special noncollinear AOTF system, in which the central optical wavelength could be tuned continually by rotating the AOTF, rather than changing its RF. This arrangement is confirmed to be effective to broaden the work wavelength range of a traditional RF based AOTF with the high spectral resolution. Particularly, it is welcomed to the circumstance for the flexible spectral bandwidth. This work has presented not only an original way to tune the wavelength of the filtered optical signal but also a powerful supplement of the RF controlled AOTF. It can lead to a wider applications of a noncollinear AOTF in the field of spectral analysis, hyperspectral imaging, and etc.