In the area of online teacher training, asynchronous collaboration faces several challenges such as limited learner engagement and low interaction quality, thereby hindering its overall effectiveness. Drawing on social comparison theory, providing social comparison feedback to teacher-learners in online asynchronous collaborative learning offers benefits, but also has drawbacks. While social comparison has been explored in diverse fields, its role in education remains unclear. In this study, we selected 95 primary and secondary school teachers participating in an online training course. Using randomized controlled trial design, we provided the experimental group with social comparison feedback, while the control group received only self-referential feedback. We used epistemic network analysis, lag sequential analysis, and social network analysis to identify the impact of social comparison feedback on group-regulated focus, group-interactive behaviors, and social network structures. The results showed that social comparison feedback significantly enhanced teachers' online asynchronous collaborative learning.