Background: Vocal music education is a skill-oriented course. Students not only need to improve their skills through repeated practice, but also need to learn self-reflection on their singing skills to achieve improvement in their vocal music performance. To promote students' reflection, previous studies have introduced peer assessment (PA) in vocal music courses, allowing learners to evaluate the work of others to promote self-reflection and innovate traditional patterns of vocal music instruction. Objective: Studies have indicated that, without proper scaffolding, learners with limited knowledge often have difficulty providing high quality comments and sometimes even provide no feedback to their peers. To solve this problem, the current study integrated the structural reflection-promoting mechanism into PA in a vocal music course at a university. Method: To verify the effects of the proposed approach, a quasi-experimental study was conducted to investigate the effectiveness of the approach with a total of 22 students recruited as the experimental group and 23 students as the control group. Results and Conclusions: The findings showed that the approach greatly improved the vocal music performance of the experimental group students, as well as their learning attitudes, self-efficacy and critical thinking. Furthermore, the interview was conducted to investigate learners' perceptions of and learning experience with the proposed approach.