Objective To establish a reproducible rat model of acute rectal mucosal injury induced by acetic acid. Methods Fifteen healthy Sprague-Dawley rats were randomly divided into the control group (3 rats) and experimental group (12 rats). Acute rectal mucosal injury was induced by 4% acetic acid using a cotton swab inserted into the rat rectum for 1 min to a depth of 3 cm. The morphological characteristics were analyzed by the naked eye and histology at 0.5 h and 1, 4, and 6 days after acetic acid intervention. Results All rats survived 6-day study period. The successful rate of model establishment was 100%. From 0.5 h to 1st day after acetic acid intervention, the gross morphology of recta showed congestion, edema and ulcer to ulcer complicated with hemorrhage. The histology showed necrosis and hemorrhage of the epithelial tissue of the mucosa to complete and extensive necrosis of the mucosa. The glandular structure showed partial to complete loss. The submucosa showed edema to edema complicated with hemorrhage and congestion. The interstitial tissues showed vasodilatation and congestion to inflammatory cell invasion.From 4 to 6 days after acetic acid intervention, the rectal mucosal changes were obviously improved. Epithelial and glandular regeneration and inflammatory granulation occurred, but not fully recovered, some edema and redness, partial lack of glands were still present. Conclusions 4% acetic acid for 1 min can be used to successfully induce rat model of acute rectal mucosal injury. This procedure is easy to operate, with a high success rate, reproducible, and the alterations are lasting more than 6 days. This animal model is very suitable for rapid screening of topical drugs for the treatment for rectal mucosal injury.