In order to understand the flocculation and separation processes of fermentation broth and improve the separation efficiency，this paper，at a microscale，examined the influence of shearing force and size of flocs in the flocculation process of fermentation broth on the effect of removing the flocs by filtration.With micronomicin fermentation broth as the research target，the research changed the shearing force on the flocs in the flocculation process.The size and size distribution of the flocs under different shearing forces were measured within 0.02—2000 μm with a laser particle size analyzer.The filtering rate and settling rate of the flocs were determined.The experiment results showed that the size of the flocs decreased with increasing shearing force and the size distribution span of the flocs increased with increasing shearing force.The settling rate of the flocs increased with increasing size of the flocs; under a moderate shearing force，the flocs had a moderate size and size distribution span and a bigger compaction degree，and the filtering rate of the flocs reached a maximum value.The experiment results indicated that the shearing force in the flocculation process evidently affected the size，size distribution span and compaction degree of the flocs and affected the filtering rate and settling rate of the flocs.