Textbook use is a core component of textbook development, yet existing research on secondary school geography textbook use has paid limited attention to teacher-level case studies. Grounded in the Grounded Theory, this study takes secondary school geography teachers as the research subjects. Through research methods including classroom observation, semi-structured interviews and artifact analysis, it examines teachers' textbook use behaviors from three dimensions: textbook comprehension status, textbook processing strategies, and curriculum implementation forms. Specifi cally, textbook comprehension status is classifi ed into three levels; textbook processing strategies, which target the main text, columns and images of textbooks, are divided into fi ve forms: retention, replacement, supplementation, deletion and adjustment; curriculum implementation forms are categorized into three orientations: fi delity, mutual adaptation and enactment. This study further reveals the multiple factors infl uencing teachers' textbook use, covering dimensions such as teachers' personal background, student performance, textbook evaluation, teaching effectiveness, and external environment. These factors interact and intertwine across diff erent time dimensions, jointly shaping teachers' behaviors in textbook comprehension, processing and implementation.