Abstract: Objective: To study the content and chemical composition of crude polysaccharides from different parts of Urtica macrorrhiza Hand.-Mazz. and evaluate their regulatory effect on macrophage. Methods: The crude polysaccharides from the roots, stems and leaves of Urtica macrorrhiza Hand.-Mazz. were prepared by hot water extraction and ethanol fractional precipitation. Their molecular weight and monosaccharide composition of the polysaccharides were analyzed by high performance liquid chromatography (HPLC) and their structural characteristics were identified by full-wavelength scanning and infrared spectroscopy. The cytotoxicity of these polysaccharides was evaluated by MTT assay. The effect of polysaccharides on the phagocytic activity of macrophages was investigated by neutral red staining and their effect on the secretion of NO and TNF-α from macrophage was studied by Griess method and ELISA, respectively. Results: Six kinds of crude polysaccharides were extracted from leaves (UML40, UML60), stems (UMS40, UMS60) and roots (UMR40, UMR60), of which the highest yield of 4.62% was obtained from leaves, 77.92% from UML40, 0.69% from stems and 1.13% from roots. The average heavy average molecular weight of each crude polysaccharide ranged from 2.11 kDa to 802.21 kDa and consisted mainly composed of D-glucose, D-galactose, D-arabinose and D-galacturonic acid, while the molar ratio of monosaccharide components was various in different parts. In addition, the immune activities of polysaccharides from different parts with different molecular weights were obviously different, UML40, UMS40 and UMR40 could significantly activate macrophages, promote their phagocytosis activity, and increase their secretion of NO and TNF-α (P<0.05). Although UMR60 had no obvious effect on macrophage phagocytosis, it could significantly promote cytokine secretion (P<0.001). Whereas, UML60 showed higher cytotoxicity and lower activity, and UMS60 did not showed activity in activating macrophages. Conclusion: Polysaccharides from different parts of Urtica macrorrhiza Hand.-Mazz. varied in monosaccharide composition and immunomodulatory activity, thus quality control would be important for the research and development of these polysaccharides.