Biomicroparticles such as proteins, bacterium, and cells are known to be viscoelastic, which significantly affects their performance in microfluidic applications. However, the exact effects and the quantitative study of cellular viscoelastic creep within different applications remain unclear. In this study, the cellular-deforming evolution within a filter unit was studied using a multiphysics numerical model. A general cellular creep deformation process of viscoelastic particle trapping in pores was revealed. Two featured variables, namely, the maximum surface displacement and the volumetric strain, were identified and determined to quantitatively describe the evolution. The effects of flow conditions and physical characteristics of the microparticles were studied. Furthermore, a Giardia concentration experiment was conducted using an integrated hydraulic filtration system with a porous membrane. The experimental results agreed well with the numerical analysis, indicating that, compared to pure elastic particles, it is more difficult to release cellular material matters including cells, chemical synthetic particles, and microbes from trapping due to their time-accumulated creep deformation.