Abstract: In order to evaluate the anti-inflammatory effect of crude polysaccharide from Tibetan Opuntia ficus-indica stems, the impacts of crude polysaccharide contents on the foot swelling in mice caused by carrageenin, and on the contents of inflammatory factors in mice’s plasma were studied, through the infrared spectroscopy analysis of the crude polysaccharide from Opuntia ficus-indica stems, and the determination of the molecular weight and contents of total sugar as well as monosaccharide composition and contents. The results showed that the characteristic groups of crude polysaccharide from Tibetan Opuntia ficus-indica stems were mainly centered on stretching vibration and bending vibration. The stretching vibration was manifested as primary amine and -NH stretching vibration of primary amine, -C=C- and C-O stretching vibration; the bending vibration as -OH bending vibration, C-O asymmetric shrinking vibration and C-CO-C bending vibration in plane. The contents of total sugar was 405.724 mg/g, the molecular peak (Mp) of total sugar was 24915 Da, and the monosaccharide was mainly composed of D-glucose (Glc). In the range of 100~400 mg/kg, with the increasing of the polysaccharide dose, the degree of foot swelling of mice decreased and the inhibitory rate of foot swelling increased. The inhibitory rate of polysaccharide from the stem of Tibetan Opuntia ficus-indica on mouse foot swelling was better, showing a dose-dependent trend. The expression levels of IL-1β, IFN-γ and TNF-α inflammatory factors in the high-dose team of crude polysaccharide from stems were closest to the expression levels in its positive control dexamethasone acetate team. The expression levels of IL-1β, IFN-γ and TNF-α inflammatory factors decreased as the concentration of crude polysaccharide from stems increased, which explained that crude polysaccharide from Tibetan Opuntia ficus-indica stems had a favorable anti-inflammatory effect.