Abstract: After comparing the existing techniques of diffraction analysis of SAW-IDT,this paper presents a new broadband analysis method.Begining with the charge distribution and Green function,this paper derivates the rigorous angular spectrum of wave and impulse-response model,the substrate anisotropy and propagation character are included,and the broadband analysis of diffraction in frequency domain is given.The simulation proves that this method is very precise and can be used in design and compensation of high performance wideband SAW filters.