Abstract: Due to its good particles trapping properties， filter screen is widely used in industrial or civil fields. However， the research on its micro-capture mechanism is still limited. In this paper， a set of microscopic observation system was set up to record the whole process of filter screen trapping particles. The microscopic performance of the process of particles trapping was studied. The influencing factors that affect single fiber filtration and mesh bridging blockage were analyzed. The results show that with the increase of filtration velocity， the ratio of unblocked pore area to total pore area gradually decreases， and eventually a stable state will appear. With the increase of mesh number， the ratio gradually decreases. In the actual application， the filtration velocity and filter screen pore size should be properly selected according to the specific conditions of use. The filter screen should be cleaned in time to avoid secondary pollution.

Key words: filter screen, trapping mechanism, microscopic observation, bridging, mesh blockage