The results show that: (1) the overall learning effect of synchronous interaction is significantly higher than that of asynchronous interaction, especially in the learning of conceptual and reflective knowledge. (2) the interpersonal neural synchronization in the area of the left prefrontal and temporal cortex of human realizes the good interaction between teachers and students and play a fundamental role for online Chinese Second Language Teaching-Learning,  the Interpersonal neural synchronization (INS) is significantly associated with a significant learning effect, to verify the view that " ‘INS’ is the neural marker to measure the quality of interaction between teachers and students", this view is extended to the field of Chinese Second Language Interactive Learning. The neurobiological basis of synchronous interaction for better learning results is that the INS between teachers and students occurs in a larger area of the brain. (3) INS in the guide-link of teaching process in synchronous interaction mode, which involves more interaction, influence students learning effect, while in the asynchronous interactive mode, INS in the interpretation link which involves less interaction, influence students learning effect. The reason is that teachers under synchronous interaction provides targeted feedback based on students answer, which is associated with more positive attention, mood, teacher-student relationship, and more moderate cognitive anxiety. In conclusion, the feedback behavior in teacher-student interaction is of vital importance for Second Language Learning.

This study has enriched research results of online Chinese Second Language Teaching modes  by empirical quantitative, provides examples of Chinese Second Language interaction between teachers and students for the conclusion that “INS is one of the neural markers to measure the quality of interaction between teachers and students”, enrich the theory of Interaction Hypothesis of Second Language Acquisition, and provides reference to guide the choice of synchronous and asynchronous lessons and the design of each teaching link in the field of Chinese Second Language Teaching.