Promoting cross-disciplinary thematic learning is the key path to implementing Geographical key Competences. Cross-disciplinary teaching integrating "Geography + History" breaks down disciplinary barriers and helps students construct a complete cognitive system of space and time. Based on the theory of spatial-temporal narrative, this paper takes the archaeology of the Mogao Grottoes in Dunhuang as a specifi c case to explore the implementation path of "Geography + History" cross-disciplinary teaching. A practical eff ect survey shows that 85% of students in the experimental class can accurately construct a spatial-temporal cognitive framework, and 78% can comprehensively analyze the relationship between the development of the Mogao Grottoes and their spatial-temporal background, which are significantly higher than that of students in the control class. The research can provide reference cases and strategies for cross-disciplinary teaching of geography in middle schools, and facilitate the cultivation of Geographical Key Competences.