Abstract: The leaky Rayleigh wave, an inhomogeneous surface wave,exists at the interface between a fluid half space and a solid half space.The secular equation of leaky Rayleigh wave is derived and the formulas ofparticle displacement and stress distributions in the inviscid fluid and theisotropic solid are presented. The characteristics of leaky Rayleigh waves,the particle displacement and stress distributions in the fluid and solidare investigated with numerical results using those equations. The effect ofthe fluid-solid density ratio on the velocity and attenuation of leakyRayleigh wave and its particle displacement and stress distributions in thefluid and the solid is analyzed numerically. The leaky Rayleigh wave isnon-dispersive and attenuate with propagetion distance. Its velocity andattenuation increase with the fluid-solid density ratio. The fluid-soliddensity ratio has significant effect on the vertical displacement but littleon horizontal displacement in the solid half space. The fluid-solid densityratio also dramatically effects on the vertical normal stress and shearstress but little on horizontal normal stress in the solid half space. Thetheory is promising to be explored to nondestructive testing and evaluationwith leaky Rayleigh wave.