<p>Understanding the mechanism of teacher performance within conceptual change teaching stands as a pivotal focus within educational research. This study endeavors to delve into the evolution of teachers' professional growth within the theme of conceptual change, highlighting the transition from theoretical understanding to practical implementation. Employing a one-year training initiative utilizing the Workshop-Seminar-Demonstration Class model, 26 junior high school science teachers were engaged. With the analysis of teacher interviews, lesson plan designs and classroom videotapes, this study divides the conception part of teachers into four stages and the practice part into three modules. As teachers progress through these stages, they encounter increasing barriers, resulting in a funnel-like pattern of diminishing achievements. Overall, teachers perform better in transmitting conceptions during the middle phase of instruction. This is followed by moderate effectiveness in addressing students' preconceptions at the beginning of the lesson, while the weakest performance is observed during the evaluative phase at the end, which remains challenging to improve through professional development (PD) training. The findings highlight the potential of interdisciplinary PD programs to support conceptual change teaching. However, they also reveal that teachers exhibit selective application of newly acquired instructional strategies in practice. This selectivity appears to be influenced by exam-oriented priorities, prompting teachers to favor approaches that directly enhance students' assessment outcomes. These empirical insights not only enrich our understanding of the mechanisms underlying teachers' engagement with conceptual change teaching strategies but also furnish valuable guidance for the design and implementation of future professional development endeavors in this domain.</p>