Abstract: In this work, sound speeds with different pressures and different water contents are measured by using the time-of-flight method. Acoustic attenuation and nonlinear acoustic characteristics of dry and wet glass bead samples are analyzed with Fourier transform method. The results show that sound speed, acoustic attenuation coefficient and harmonic nonlinearity in the dry and wet glass bead samples vary with the pressure in the form of power law, and sound speed gradually increases with the increasement of liquid content in wet samples, and the energy dissipation and nonlinearity of ultrasonic waves through the wet samples gradually decrease. Pressure and pore fluid change the inter-particle contacts distribution, resulting in changes in elastic modulus, energy dissipation, as well as the number of internal weak contacts in the granular systems. The above results clarify the obvious effects of both pressure and pore fluid on the sound speed, attenuation and harmonic nonlinearity of wet granular systems.