“Image” is one of the most representative thinking styles in TCM. It is closely connected with Chinese ancient culture. The extensions and changes of the meaning of this term are mostly involved in the attempts of the ancients to communicate with heaven. As the rise of human rationality at the end of Xizhou dynasty， its meaning was transformed from “Guixiang” and “Yixiang” in the context of religious theology to “Daoxiang” and “Qixiang” in the Spring and Autumn Period， and finally to the meaning formalized and systemized by “lei” affected by the systematic model of the cosmos in Qin and Han dynasty. There was a common cognitive sign pattern mediated by “image” that kept unchanged during the whole evolution. It was just based on these achievements that the theoretical system of TCM characterized by “image” was fully formed in these periods.