The configuration and testing principle of DW1 MediumBlockingType fluid contamination level measurer were simply introduced. The threedimensional image of flow field around micropore filter membrane sensor was imported to the Fluent software, and the mathematic model for analyzing the flow field was established. Based on Fluent, the velocity field, the pressure field and the fluid trajectory during testing with DW1 fluid contamination level measurer were analyzed. The results show that the flow field is centrosymmetric, two eddy regions have little influence on the whole flow field, and the velocity and the pressure jump down during the porous zone since the influence of viscosity resistance. Increasing the pipe diameter in the inlet region can get a larger transmembrane pressure. Visualization of detection process was realized by flow field simulation method, and the simulation results can provide a reference for improving the structure of MediumBlockingType fluid contamination level measurer.