Cavitation-silt erosion in sand suspensions has elicited research attention. However, erosion characteristics in various conditions of liquids remain unknown due to their complex mechanisms. Thus, the effects of sand size, concentration, and temperature of sand suspensions on cavitation-silt erosion and viscosity were experimentally investigated in the present work. The findings proved the existence of critical sand size. The silt-cavitation erosion decreased with the increase of sand concentration when the sand was smaller than the critical size, and it increased with the increment of the sand size and temperature. A good relationship between the viscosity and the sand size, concentration, and temperature was determined. Moreover, the cavitation-silt erosion mechanisms were obtained on the basis of the viscosity and impingement erosion analysis standpoint.