It's known that under cross-flow microfiltration, the major factors influencing cake formation as well as the overall filtration resistance were found to be the hydrodynamic forces exerted on the membrane. Therefore, the filtration rate increased with the increase of the cross-flow velocity and filtration pressure under a wide range of conditions. In this work the simulating geometry of the cross-flow microfiltration was established, the meshes were constructed, and the boundary conditions were set, then the velocity field, the total filtration resistance, and the shear force distribution on the membrane surface could be calculated directly. Then we compare these numbers obtained from simulations with experimental results. Also, we use the idea of the side-stream in this study with the hope of altering fluid dynamics inside the channel, which in turn causes changes in the shear force on the membrane. Combining the filtration rate obtained in experiments and the computational fluid dynamics (CFD) software, we attempt to improve fouling condition on the membrane and to observe alterations in the shear force on the membrane, all with the eventual goal of improving the filtration rate. The force analysis on the membrane surface is a tool for decaying fouling rate on the membrane and improving the efficiency of the cross-flow microfiltration. This CFD-aided design could help to effectively increase the permeate flux, reduce the fouling on the membrane and extend the washing cycle during filtration. Finally, we also discuss the varying average porosity of cake.