Abstract: In conversations, people often reuse the words, phrases, and syntactic structures of the former speaker in the immediate context. These echo utterances are frequently seen in doctor-patient conversations and are considered as a kind of communicative and interactive resource. This article uses the naturally occurring preoperative conversation between doctors and patients as the research corpus, adopts the method of conversation analysis and proposes an echo utterance triangle model based on Du Bois' theory of dialogic syntax. With this model and Diagraph (Du Bois), echo utterance and its resonance in Chinese doctor-patient interaction are analyzed from the aspects of form, function and communication. It found that:1) Chinese echo utterances are dynamic and enable intersubjectivity, and associated with a special interaction intention, they are used to adjust the interlocutor's epistemic gradient. 2) the resonance between the echo utterance and the echo source in the doctor-patient interaction can be specifically embodied as receiving resonance, inspective resonance, interrogative resonance, emphasized resonance, connection resonance and confirmatory resonance. This study aims to broaden the understanding of the echo utterance phenomenon and to shed light on the optimization of doctor-patient communication.