Ulcerative colitis (UC) is a common gastrointestinal disease in clinic, which belongs to the category of “dysentery” in traditional Chinese medicine. The connotation of damp-heat and turbid toxin is the key to the recurrence and lingering of UC. In ancient prescriptions, Huanglian (Coptidis Rhizoma) is the best treatment for dysentery, and its functions of clearing heat and drying dampness, purging fire and detoxifying are in line with the pathogenesis. Studies have shown that Huanglian (Coptidis Rhizoma) can effectively relieve symptoms when used alone, but it can better exert its efficacy when used in combination with other Chinese medicines. Huanglian (Coptidis Rhizoma) is often combined with Huangqin (Scutellariae Radix) and Huangbo (Phellodendri Chinensis Cortex) which are heat-clearing drugs to strengthen the function of clearing heat and drying dampness and treat all damp-heat dysentery. It is often used with blood drugs such as Danggui (Angelicae Sinensis Radix), Baishɑo (Paeoniae Radix Alba) and Ejiɑo (Asini Corii Colla) to nourish Yin and remove heat, and treat dysentery due to Yin deficiency. It is often combined with Qi-regulating drugs such as Muxiang (Aucklandiae Radix), Houpo (Magnoliae Officinalis Cortex), Chenpi (Citri Reticulatae Pericarpium) and Zhiqiɑo (Aurantii Fructus) to regulate Qi and relieve pain and treat Qi-stagnation dysentery. It is often combined with drugs for warming the interior like Ganjiang (Zingiberis Rhizoma) and Wuzhuyu (Euodiae Fructus), which can be used for both cold and heat to harmonize Yin and Yang and treat cold and heat dysentery. In addition, this paper discussed the matters needing attention in the application of Huanglian (Coptidis Rhizoma) in UC from four aspects: cautious use of deficiency cold, improper use of deficiency heat, stopping when and food taboos.