This study was conducted in order to evaluate the ameliorative effect of polysaccharides from Chinese yam treated with the fermentation broth of Bacillus sp. to inhibit browning on acute colitis induced by 3% dextran sulfate sodium (DSS) in mice. The results showed that the polysaccharides significantly reduced the disease activity index (DAI) of mice with colitis (P < 0.01), alleviate colon atrophy (P < 0.05), decreased the secretion of tumor necrosis factor-α (TNF-α) (P < 0.01) and colonic histopathological score (P < 0.05), and increased the diversity of intestinal flora by increasing the abundance ratio of Firmicutes to Bacteroidetes and the relative abundance of beneficial bacteria such as Roseburia and reducing the relative abundance of harmful bacteria such as Alistipes. Similar effects were observed with those from Chinese yam treated with water. Likewise, the polysaccharides from Chinese yam treated with the fermentation broth of Bacillus sp. ameliorated DSS-induced colitis in mice, and the underlying mechanism may be related to the regulation of the intestinal flora and the secretion of pro-inflammatory factors. These results provide theoretical reference for the processing of Chinese yam and the research and development of functional foods containing Chinese yam polysaccharides.