Abstract: To prepare a budesonide rectal thermogel. The gel solution was prepared by cold method, and the gelation temperature of the gel solution was determined by reverse tube method. The amount of poloxamer 407(P407), poloxamer 188(P188)and hydroxy propyl methyl cellulose(HPMC)was optimized by central composite design/response surface method. The in vivo gelation character was investigated after rectal administration of the budesonide thermogel into the rat, and the in vitro drug release from the gel was examined by the Franz diffusion cell method. Finally, the optimal formulation includes 0. 002% budesonide, 0. 93% HPMC, 2. 00% P188, and 18. 31% P407. It is preferable to obtain the appropriate formulation for budesonide rectal in situ thermogel, which can achieve wide distribution and adhesion to the rectum, as well as long-term drug release.