The game-based learning approach to developing students' computational thinking (CT) current has received attention from researchers. However, the compatibility between games and instruction is often insufficient to accommodate the entertaining and educational nature of the curriculum entirely, and the benefits of game-based learning could be compromised. Therefore, this study proposed a role-playing-based micro-game strategy for developing students' CT in a Python programming course, and designed a quasi-experiment to verify the effectiveness of the role-playing-based micro-game strategy. A total of 133 eighth-grade students from schools in eastern China were randomly divided into experimental and control groups. The experimental group used a role-playing-based micro-game strategy, and the control group used a traditional instructional strategy. The results showed that the experimental group scored significantly higher than the control group on the CT test, especially in the dimensions of computational concepts and computational practices. The learning engagement of the experimental group was significantly higher than that of the control group, and the learning motivation of the experimental group was significantly improved before and after the experiment. In addition, qualitative analysis of the interview data indicated that micro-game strategy on role-playing could promote classroom learning and meet the needs of the course knowledge system.