Abstract: To explore the effect and mechanism of sodium propionate and mixed short-chain fatty acids on colitis induced by Citrobacter rodentium (C.r.) in mice. Mice were induced by oral gavage of C.r. The C.r. growth monitoring, histopathological analysis, qPCR analysis, intestinal permeability test and flow cytometry was used to study the effects of sodium propionate and mixed short-chain fatty acids on intestinal infection. The results showed that sodium propionate could inhibit the growth of C.r. more effectively than mixed short-chain fatty acids. Results of animal experiments showed that sodium propionate significantly reduced the weight loss and intestinal bacterial output in mice. Meanwhile, compared with mixed short chain fatty acids, sodium propionate effectively alleviated the pathological manifestations of colonic inflammatory infiltration, destruction of epithelial cell structure and decrease of goblet cell caused by C.r. infection, also increased the levels of antimicrobial peptides like interleukin-17 (IL-17) and regenerated islet derived protein 3γ (Reg3γ). In addition, sodium propionate decreased intestinal permeability better than mixed short-chain fatty acids, and sodium propionate significantly induced T helper cells 17 (Th17) and regulatory T cells (Treg) differentiation. The results showed that sodium propionate significantly alleviated colitis induced by C.r. infection compared with mixed short-chain fatty acids, which may be related to its inhibition of C.r. growth and enhancement of intestinal anti-infective function. The expected results can provide a safer and effective treatment strategy and scientific basis for colitis.