The quality of music education is fundamentally linked to the specialized knowledge of teachers. Pedagogical Content Knowledge (PCK), as conceptualized by Shulman and further developed by Grossman, represents the unique integration of content and pedagogy that distinguishes expert teachers. While globally recognized, research on excellent music teachers in China has often been anecdotal rather than empirical, creating a gap in understanding the cognitive structures that underpin high-quality teaching and hindering targeted professional development.This study aims to by empirically investigating the structural characteristics of PCK among excellent music teachers in mainland China. Grounded in Grossman's framework, the research focuses on identifying not only the core components of their PCK but, more importantly, how these components are organized and integrated in practice. The central goal is to map the complex, dynamic knowledge systems that enable these teachers to create effective and responsive learning environments.A multiple-case study methodology was employed to gain in-depth insights. Fifteen excellent music teachers, selected through criterion and intensity sampling from across China, participated in the study. Data were constructed through extensive fieldwork for each participant, including semi-structured interviews, sustained classroom observations, and analysis of artifacts like teaching diaries. To analyze the data, a modified version of Park & Chen’s PCK analysis map was utilized to visually represent the constituent elements of PCK and the density of their interrelationships within teaching episodes.The analysis reveals three defining features of excellent music teachers' PCK. First, their knowledge structure contains complete and rich components, with deep cognitive schemas across Grossman’s domains. Second, these components are organized in a highly interconnected, web-like structure, contrasting sharply with the more linear or fragmented knowledge of novice teachers. This web-like integration enables them to fluidly connect curriculum, student understanding, and pedagogy. Third, their practice shows a profound unity of knowledge and action, where espoused beliefs align with practice and knowledge becomes embodied through passionate, authentic teaching.This study provides an empirical model of expert music teacher knowledge in the Chinese context. It concludes that fostering expertise requires cultivating the intricate, web-like integration of knowledge, not just accumulating discrete components. For professional development, this implies a shift towards pedagogies like case-based analysis and reflective practice that prioritize knowledge synthesis in context. By understanding the "unity" within an expert's practice, we can "build bridges" to support the growth of all educators, offering insights for both Chinese and international music education communities.