Abstract: To study the influence of saturation on the ultrasonic shear wave propagation law of rocks, with red sandstone as the research object, ultrasonic shear wave propagation tests were conducted with frequencies of 50, 100 and 200 kHz under different saturations, and the variation law of saturation and frequency on shear wave acoustic parameters were analyzed. The results show that the shear wave velocity decreases nonlinearly with increasing saturation, and the amplitude attenuation coefficient increases nonlinearly with increasing saturation, both of which meet the cubic function relationship and are highly correlated. The overall analysis shows that the influence of saturation on shear wave velocity is greater than that of the amplitude attenuation coefficient, and the fitting parameters of the amplitude attenuation coefficient can better reflect the changes in physical quantities of rock samples. Based on the comprehensive consideration of sensitivity and determination coefficient, it is suggested to use 100 kHz as the dominant frequency of ultrasonic shear wave testing for water-bearing sandstone in the future. The research results can provide a reference for the development of rock ultrasonic testing technology under different saturations.