The characteristics of the integrated optical acoustooptic tunable wavelength filter have been theoretically analyzed. A practical device with central wavelength of 1.523 μm has been fabricated on x-cut Y-propagation LiNbO3 substrate. The effective acoustooptic interaction length in this device is 16 mm and a TE-TM mode conversion efficiency of 99.3% has been achieved with only 35 mW of RF drive power. The tuning wavelength range is 140 nm with a FWHM of 1.6 nm. The over (fiber to fiber) insertion loss is -4 dB.