Gaofeng Yuanmiao (1238-1295) was a Chan master of the Linji school between the Sung and Yuan dynasties. He was well-known for his proficiency in “Kanhua Chan”, a uniquely sinitic form of meditation handed down from South Sung. This thesis discusses Gaofeng’s Chan thought and practice by analyzing the content of his two texts, Gaofeng yuanmiao chanshi chanyao and Gaofeng yuanmiao chanshi yulu. I discuss Gaofeng’s ideas on the theory basis, main purpose, and main principle of the Kanhua Chan, and discuss Gaofeng’s methods of huatou investigation: “great faith”, “great zeal”, and “great doubt” as the “three essentials” for accessing awakening. Moreover, I describe four implied functions of huatou investigation. These are (1) the “cultivation of the prajñā seeds”, (2) “fusion into wholeness”, (3) “accessing the no-mind samādhi”, and (4) “passing the patriarchs’ barrier”. An important aspect of this thesis is that it is the first original research to focus on Kanhua Chan in the Yuan dynasty, such that the results can be applied into practice for those doing huatou practice.