In this study, the microfiltration of polyester fluid containing solid suspension has been investigated under constant pressure. A membrane module, which consists of a microfilter paper of surface area of 19.4 cm(2) and a SS-316 net support (160 mesh), was used. It was found that the homogeneous sodium acetate suspension in polymer can be completely removed by the membrane filter paper to yield a very clear polymer product. The property and rheology of polyester fluid with suspending solids have been studied. The polymer fluid can be viewed as a Newtonian fluid in this work. The filtration behavior in the membrane system was simulated by the blocking filtration law. Satisfactory fit between experimental data and theoretical calculations was demonstrated.