Three kinds of knowledge that effective teachers should master have been proposed: content knowledge (CK), pedagogical knowledge (PK), and pedagogical content knowledge (PCK). Most PCK studies have been conducted in the mathematics or science domain. In recent years, a growing number of studies related to foreign language teachers' PCK have appeared. However, there is a paucity of studies that explore teachers' PCK in the field of Chinese as a foreign language (CFL). In this study, we present a conceptualization of Chinese as foreign teachers' PCK when they teach Chinese pronunciation. The research design builds on semi-structured interviews involving 20 CFL teachers (n = 20), focusing on five PCK domains: (1) teachers' knowledge of Chinese pronunciation subject content (initials, finals, tones, intonation, and stress), (2) their curriculum knowledge, (3) their knowledge of students' mistakes and difficulties, (4) their knowledge of Chinese pronunciation-specific instructional strategies, and (5) their knowledge of instructional media. The results show that CFL teachers reflect a strong mastery of PCK concerning teaching tones, followed by initials and finals. Teachers' PCK regarding teaching intonation and stress were much weaker in all five PCK components. Their PCK of teaching intermediate-level and advanced-level students was also limited by curriculum and time arrangement restrictions.