Four novel Mesona chinensis Benth polysaccharides were isolated using aqueous alcohol precipitation. Their molecular weights were determined using high-performance gel permeation chromatography: MA1 (2.3 kDa), MA2 (80.5 kDa), MA3 (180.9 kDa), and MA4 (635.2 kDa), and their compositions were analyzed using GC-MS. The polysaccharides were mainly D-glucose, D-galactose, L-Rhamnose, D-arabinose, D-xylose, and D-mannose. The structural characteristics were further analyzed using infrared spectrophotometry and were identified as a type of pyrrhic sugar. An insulin-induced insulin resistance model of HepG2 cells and oleic acid-induced fat accumulation model of insulin were established to evaluate the hypolipidemic effects. Three Bacteroides spp. [Bacteroides thetaiotaomicron (BT), B. ovatus (BO), and B. cellulosilyticus (BC)] that were negatively correlated with lipid-lowering activity were used to evaluate the lipid-lowering activity of polysaccharides. The Bacteroides metabolites of MA1 and MA2 exhibited hypolipidemic effects and antioxidant activities and could potentially be used as lipid-lowering supplements.