The phagocytosis of PMNs plays an important role in the process of resisting bacterial, fungal and other pathogenic microorganisms infection. The process of phagocytosis consists of several major stages: chemotaxis, adhesion, endocytosis, intracellular oxygen-dependent (respiratory burst) and oxygen-independent killing.  Under normal conditions, PMNs are activated after bacterial infection, and the enhancement of PMNs phagocytosis and oxidation is an important innate immune defense mechanism of the body. Therefore, by observing the activation status of PMNs, we can help to understand the bacterial infection status of the organism.  PMNS function was detected by flow cytometry (FMC), PMA was used as high performance stimulant, and dihydroardamine was used as fluorescence substrate. When neutrophils are stimulated, they produce reactive oxides, and rhodamine dihydrogen oxide is rhodamine 123, which can emit fluorescence. This reaction can be terminated by hemolysin.The reactive oxides produced can be expressed in terms of fluorescence intensity.PMNS activation and the body's innate immune capacity.It can be used to study the functional changes of neutrophils in various pathological conditions, such as infection, autoimmune disease, emergency, tumor, surgery, etc., and to evaluate the effect of drugs.The kit can be used not only in humans, but also in mice, rats, rabbits, dogs, cattle and other species.