The velocity and attenuation changes of shear horizontal surface acoustic wave (SH-SAW) biosensors with viscosity changes as a function of the operating frequencies are studied. It is confirmed that the velocity and attenuation changes of SH-SAW biosensors to the viscous changes are proportional to the square root of the frequency using the numerical calculations and experimental results. On the other hand, there are two more design parameters to determine a sensitivity of the SH-SAW biosensors, the gold film thickness of the propagation area and the length of the propagation area. A 380MHz SH-SAW biosensor is designed and fabricated on quartz substrates, and tested using different concentrations of glycerol mixtures. Very good agreements between theoretical and experimental results were obtained.