Interaction between two spheres with an interstitial fluid is essential in Discrete Element modeling for simulating the behaviors of ’wet’ particulate materials. In this paper the interaction between two spheres with an interstitial Power-law fluid was approximately resolved as normal and tangential interactive models respe ctively, for which the governing equations were simplified on the basis of Reynolds approximation. These equations were then solved analytically together with the boundary conditions to obtain the pressure distributions for each individual model, and event u-ally solutions of the viscous squeeze force and the tangential viscous resistance were obtained, which provide a set of solutions for implementing into DEM code or other purposes. Interaction between two spheres with an interstitial fluid is essential in Discrete Element modeling for simulating the behaviors of ’wet’ particulate materials. In this paper the interaction between two spheres with an interstitial Power-law fluid was approximately resolved as normal and tangential interactive models respe ctively, for which the governing equations were simplified on the basis of Reynolds approximation. These equations were then solved successfully with the boundary conditions to obtain the pressure distributions for each individual model, and event u-ally solutions of the viscous squeeze force and the tangential viscous resistance were obtained, which provide a set of solutions for implementing into DEM code or other purposes.