We use Joness matrix method and the global optimal method to investigate the propagation characteristic of surface acoustic wave(SAW) for X-cut single crystal Lithium Niobate(LiNbO₃). As an application, a novel integrated acousto-optical filter, which allows to minimize the dimension of AO cells and suppress side-lobes, was designed on the base of LiNbO₃ crystal. Supported by the National Natural Science Foundation of China (No. 60478036)