Collaborative learning contributes to cultivating students' higher-order thinking, yet it often encounters practical dilemmas such as insufficient collaborative contexts and low-quality interaction. The integration of immersive virtual reality (IVR) and twin digital human technology makes it feasible to create an immersive and embodied environment for collaborative learning. However, the collaborative learning activities in related research mostly take place outside virtual spaces, which difficult to fully reflect the actual impact of IVR environment on collaborative learning. Based on this, the paper constructed a theoretical framework for Twin Digital Humans Empowered Collaborative Learning (THCL) in the IVR environment and used this framework as a guide to carry out a virtual simulation experiment on “family fire escape drill”. The experiment took 40 graduate students from X University in Chongqing as the research objects, who were randomly assigned to either the THCL group or the Virtual Reality Empowered Face-to-Face Collaborative Learning (VRCL) group to engage in collaborative learning through different approaches. Through pre-test questionnaire analysis, learning outcome questionnaire analysis, and correlation analysis, this paper found that THCL demonstrated better performance in students' procedural knowledge transfer and emotional experiences, and presented a lower level of cognitive load. In addition, lower cognitive load and positive emotional experience jointly constituted important conditions for promoting knowledge transfer. This paper, through the research, revealed the mechanism of collaborative learning in IVR environment and provided empirical evidence for the joint empowerment of educational practice by IVR and twin digital human technology.