As a kind of antibacterial and antifungal preservative, benzoic acid is widely used in foods and feeds. Recently, many studies showed that it could improve the growth and health, which should, at least partially, be derived from the promotion of gut functions, including digestion, absorption, and barrier. Based on the similarity of gut physiology between human and pigs, many relative studies in which piglets and porcine intestinal epithelial cells were used as the models have been done. And the results showed that using appropriate benzoic acid levels might improve gut functions via regulating enzyme activity, redox status, immunity, and microbiota, but excess administration would lead to the damage of gut health through redox status. However, the further mechanisms that some intestinal physiological functions might be regulated are not well understood. The present review will, in detail, summarize the effect of benzoic acid on gut functions.