This paper addresses the balancing dilemma between "boundary-keeping" and "boundary-crossing" in interdisciplinary teaching oriented by the core competencies of geography. lt proposes a professional practice framework centered on "scale grasping" as the core. lt arques that "boundary-keeping" represents a rational adherence to the subjectivity of the geography discipline, while "boundary-crossing" signifies a pedagogical innovation that actively integrates multidisciplinary resources to solve complex geographical problems. The two are dynamically unified through teachers' professional judgment. "Scale grasping" is specifically manifested in four geographical dimensions-spatiality, methodology, structure, and process-providing analyticalbases for diagnosing imbalances in teaching. This paper maintains that interdisciplinary teaching should move toward "deep integration" and achieve systematic transformation through three pathways: objective design, process organization, and eff ect evaluation, thereby off ering theoretical references and practical guidance for geography teachers in conducting interdisciplinary teaching.