Based on the wave equations of unsaturated porous medium, the dispersion equation for the Love waves in the unsaturated soil layer overlying an elastic half-space is derived with the viscous coupling between the water (gas) and the solid skeleton considered. The influence of saturation degree and frequency on the wave velocity of shear waves in unsaturated porous media is analyzed firstly. Then, the dispersion curves and displacement distributions for the various Love wave modes at different degrees of saturation are obtained and given in graphic form by use of numerical method. The numerical results show that the wave velocity and attention coefficient of the Love waves in the upper unsaturated soil layer are not only frequency-dependent, but also related to the saturation degree of the soil. The high modes Love waves (n≥2) at different saturation conditions always have different cut-off frequencies. Also, this paper discusses the influence of the saturation on the amplitude of horizontal displacement of the Love waves.