Abstract: The process of patent citation contains plenty of knowledge activities. Due to the similarity between patent and paper documents, theories and methods related to scientific metrology can be used to reveal and visually display the knowledge activity in the patent citation process. Research results show that the process of citation contains activities involoving the production, spread, development, and reorganization of knowledge. In the mesoscopic and macroscopic scales, knowledge development and reorganization on micro level may result in the change of the technology paradigm, which is similar to the scientific paradigm replacement before the arrival of the scientific revolution raised by Thomas Kuhn.