For a functionally graded piezoelectric substrate with exponential variation, the existenceand propagation behavior of transverse surface waves is studied by analytical technique.The dispersion equations for the existence of the transverse surface waves with respect tophase velocity are obtained for both electrically open and short conditions. Adetailed investigation of the effect of gradient coefficient on dispersion relation,phase velocity, group velocity and electromechanical coupling factor is carriedout. It is found by numerical examples that adjusting gradient coefficient makesthe electromechanical coupling factor of the transverse surface waves achievequite high values at some appropriate wavenumber, and at the same time, thepenetration depth can be reduced to the same order as the wavelength underelectrically short case. Because of the negligible initial stress in functionally gradedpiezoelectric materials, this model could serve as an excellent substitute for the typicallayered piezoelectric structures used in surface acoustic wave (SAW) devices, thusproviding a theoretical foundation for designing SAW devices with high performance.