In this study, we report on experimental measurements of density-driven particle ring migration on sheared granular materials with different interstitial fluid viscosities. The dimensionless sinking depth and sinking rate describe the change in the granular ring position and quantify the particle sinking speed, respectively, are successfully measured by the PTV method. The results indicate that the interstitial fluid viscosity has a significant influence on determining the density-driven particle migration of the slurry granular flows. The dimensionless sinking depth and sinking rate are the largest in a dry system (interstitial fluid of air). The particle migration becomes weaker and causes a smaller dimensionless sinking depth and sinking rate as the interstitial fluid is more viscous. Both the dimensionless sinking depth and sinking rate are enhanced with an increase in wall velocity (shear rate). The sinking rate increases linearly with the final steady-state sinking depth, regardless of the interstitial fluid viscosity and wall velocity (shear rate). (C) 2018 Elsevier B.V. All rights reserved.