Abstract: At present, the construction of the artificial intelligence curriculum in K-12 schools has been included in the national strategic development plan. However, the shortage of teachers has become the bottleneck of curriculum construction. Therefore, it is necessary to vigorously implement effective teacher professional development. Promoting teaching self-efficacy will affect teachers' teaching engagement, teaching practice and students' learning effect. Hence this study designed a professional development knowledge system based on TPACK theory, constructed a blended professional development combing with ways to improve teaching self-efficacy and effective teachers' professional development elements, and carried out a 25-days intervention with 40 potential AI teachers as participants. In terms of improving teaching self-efficacy, the data analysis results of the questionnaire and interview showed that this kind of teacher professional development significantly improved CS teachers' AI teaching self-efficacy, and caused no significant differences in CS teachers with different prior knowledge. These findings reveal the effectiveness of this professional development model in improving the AI teaching self-efficacy of K-12 CS teachers and may have a positive impact on their teaching practice and students' learning results.