Abstract: Online doctor-patient communication is the main form of online health services. The deep analysis of the knowledge asymmetry can help eliminate doctor-patient communication barriers. This article selects the online dialogue data from "Dr. Chunyu", and explores the rule of knowledge asymmetry from three dimensions: keyword topics, concept and semantic relationship. The results show that patients pay more attention to topics such as "symptom description" and "inquiry treatment", focusing on complaint and treatment stages,while doctors pay more attention to topics such as "disease explanation", and "treatment recommendation", focusing on diagnosis and treatment recommendation stages. In terms of concept understanding, doctors use more professional words and express knowledge more accurately. Doctors have more types of semantic dependencies between keywords, and stronger association strength. The research results can improve the efficiency of doctor-patient communication and promote the development of online doctor-patient communication services.

Key words: Online doctor-patient communication, Knowledge asymmetry, Concept expression, Semantic dependency, Text mining, Semantic analysis