Peer interaction is the key to promoting learners’ knowledge construction and enhancing learning effectiveness, which is conducive to developing students’ higher-order thinking. Meaningful topics can stimulate students’ interest in learning. Currently, teacher questioning and topic design are mostly mentioned as part of course instruction, and research on questioning to guide student interaction in online courses is still shallow, mostly staying at the theoretical level and proposing strategies. In view of this, the present study classifies and designs the types of topics in online forums, and explores the temporal variation of learners’ discussions and the impact of different types of topics on the level of interactive behavior and cognitive level based on the Social Epistemic Network Signature (SENS) Analysis method. The study showed that Socratic topics as tasks were more likely to attract learners’ attention and response to the topics than factual and problem-solving topics; core learners’ prestige status in the network was less affected with increasing k-core in the social network, but node activity decreased; Socratic topics in epistemic networks could enhance learners’ cognitive level of depth and breadth, and promote the formation of higher-order thinking.