The main objective was to research the process of gallnut suppository preparation with its water extract as the main drug, and evaluate its irritation to rectal mucosa. gallnut extract was obtained by decocting method, and its suppository preparation was obtained by fusion method with semi-synthetic aliphatic esters and rose flower oil as the matrix. Weight difference and in vitro melting time limit of the suppository were assayed and UV-Vis was used to determine the contents of polyphenols, tannin and saccharide. The irritation to colon mucosa was evaluated after successive administration of 14 days to New Zealand white rabbits. Finally, the prescription compositions were determined: semi-synthetic aliphatic esters and rose flower oil with the ratio of 2:1 as the proper matrix, with the drug loading of 54%. The prepared suppository was brown, conical and smooth. The weight difference was (1.43±0.03) g, with an average melting time limit of (17±2) min. The Contents of Polyphenols, tannic and polysaccharide were 332.4, 245.0, 3.3 mg•g-1 respectively in each suppository. The results also showed that the continuous administration had no irritation to rectal mucosa. It can be concluded that the suppository was an acceptable administrate form, whose preparation process was easily controlled, and with no irritation to rectum mucosa.