Rapid urbanization has intensified the shortage of school places in many developing countries, prompting the rise of compact, high-floor area ratio (FAR) school models. However, research on high-FAR school design strategies remains limited. This study systematically analyzes 67 high-FAR schools in Shenzhen, China. Using design descriptions as the sample, the analysis applied the N-gram model and identified five major design strategies: responses to regulations, functional integration of classroom spaces, functional integration of public spaces, climate adaptation and sustainability, and alleviation of psychological stress. Correlation analysis revealed that factors including FAR, total floor area, design year of the schools, regional GDP and investment in the education sector significantly influence preferences for different design strategies. Further, K-means clustering categorized four types based on strategy adoption and FAR: the comprehensive strategy type; the user-centered innovation type; the spatial integration type; the psychological well-being type. The results emphasize the need for adaptable design strategies that reflect local development stages. These findings contribute to a data-informed foundation for improving spatial efficiency in rapidly urbanizing settings, offering policy and design guidance for rapid developing cities.