The design of a SiO2 film-loaded Ti: LiNbO3 integrated acousto-optic tunable filter is reported. The configuration, in which an angular offset between the acoustic and optical waveguides is introduced, offers a good performance of suppressing sidelobes. With the mode analysis of the acoustic wave guide and the theory of coupling mode the limit of the width, weighted coupling coefficient and the characteristics of the conversion of acousto-optic modes are obtained. Considered the compromise between the sidelobes suppression and filtering bandwidth, the theoretical results are gained that the sidelobes level is -16.8 dB and the theoretical values of bandwidths of -3 dB and -10 dB is 1.37 nm and 2.31 nm.