To study the effects of Brassica rapa L. polysachharide on macrophage polarization and H226 cell proliferation and migration.The CCK-8 (cell counting kit-8) method was used to measure the B. rapa crude polysachharide (BRP),B. rapa netural polysachharide (BRNP),and B. rapa acid polysachharide (BRAP) on the cell viability of RAW 264.7 cells and the effect of BRAP on the proliferative activity of H226 cells.The mitochondrial membrane potential indicator was used to detect the effect of BRAP on the mitochondrial membrane potential of H226 cells.The effect of BRAP on the migration ability of H226 cells was detected by scratch assay.An M1/M2 macrophage model was constructed,and the effects of three polysaccharides on the secretion levels of tumor necrosis factor-α (TNF-α) and interleukin-10 (IL-10) in M1/M2 macrophages were detected by enzyme linked immunosorbent assay (ELISA).Immunofluorescence was used to detect the effects of three polysaccharides on the expression of mannose receptor (CD206) and inducible nitric oxide synthase (iNOS) proteins in M2 macrophages.Realtime fluorescence quantitative PCR (q-PCR) was used to detect the effects of three polysaccharides on the expression levels of arginase-1 (Arg-1) and interleukin-6 (IL-6) in M1/M2 macrophages.The results showed that BRP,BRNP and BRAP promoted the proliferation of macrophages and had a strong and similar effect on macrophages at 350 μg/mL,and BRAP had a significant effect on the proliferation of H226 cells,with a half inhibitory concentration of 97.84 μg/mL.BRAP decreases the mitochondrial membrane potential of H226 cells and inhibits the migration of H226 cells.The three polysaccharides could reduce the secretion of TNF-α and IL-10 in macrophages,down-regulate the expression of CD206 in M2 macrophages,and up-regulate the expression of iNOS protein.BRP,BRNP and BRAP decreased the expression of IL-6 mRNA in M1 macrophages and Arg-1 mRNA in M2 macrophages.In this study,BRP,BRNP and BRAP could inhibit macrophage polarization to M2 phenotype,and BRAP could significantly inhibit the proliferation and migration of H226 cells.This study provides a theoretical basis for B. rapa polysaccharides to inhibit tumors by regulating macrophage polarization.