The stability of the cell microenvironment is an essential condition to maintain healthy cell proliferation, metabolism, and functional activities, and the abnormality of microenvironment components can cause pathological cell changes. In this paper, the fluorescence emission characteristics and mechanism of white blood cell (WBC) in vitro in polysaccharide microenvironment were considered by fluorescence spectroscopy, and the effect of Polysaccharide on the WBC biological activity was further analyzed. The results showed that under 407 nm laser irradiation, white blood cells emit fluorescence at 450 nm. When lipopolysaccharide or dextran is added, the position of fluorescence emission peak of leukocyte will not change, but the fluorescence peak will be affected. The addition of lipopolysaccharide (LPS) can weaken the fluorescence peak intensity of leukocytes, and the higher the LPS concentration (in the range of 0～500 μg·mL-1), the lower the fluorescence intensity. While the addition of dextran can enhance the WBC fluorescence intensity to a certain extent, and the higher the concentration, the stronger the fluorescence. It believes that the 450 nm fluorescence emitted by WBC comes from the nicotinamide adenine dinucleotide (NADH). NADH is oxidized to NAD+ with the increase of cell in vitro, which leads to the decrease of fluorescence intensity and apoptosis. The hydroxyl radical (·OH) generated by adding lipopolysaccharide will react with NADH. Therefore, lipopolysaccharide accelerates the consumption of NADH, resulting in weakened leukocyte fluorescence and accelerated cell apoptosis. Dextran is mainly composed of glucose monomer, which can reduce NAD+ to NADH, thus delaying the WBC apoptosis. It believes that lipopolysaccharide can accelerate the WBC apoptosis, improve the probability of inflammation and even tumor, while dextran can protect WBC. This study is used as a valuable reference for the study of tumor occurrence, development, and treatment.