This paper discussed the nature of ulcerative colitis， that is deficiency of the root and excess of the branch， from the theory of sweat pore， and to explore the theoretical basis and experience of treating this disease with retention enema of traditional Chinese medicine （TCM）. The main location of this disease is in the intestine. As a part of sweat pore， the intestinal sweat pore serves as the gateway for the ascending， descending， exiting and entering of qi movement in the zang fu （脏腑） organs， meridians and collaterals， as well as the channel for the transportation of qi， blood and body fluids. The constraint and closure of the intestinal sweat pore are the main pathological basis of ulcerative colitis. According to the manifestations of colonoscopy， and the different etiological factors and pathogenesis that lead to the constraint and closure of sweat pore， there should be different treatment focuses such as expelling wind to open sweat pore， clearing fire to open sweat pore， promoting blood circulation to open sweat pore， for which wind-dispersing herbs， heat-clearing herbs， and blood-activating herbs are used accordingly. The method of retention enema can directly induce Chinese medicinal herbs to the affected part， so as to diffuse and unblock the sweat pore， regulate qi and blood， and thus restore the normal function of the intestinal sweat pore.