"Sun Tzu's Art of War" presents the most geopolitical thinking among ancient military books so far. The geopolitics-related chapters constitute a lot of proportion of the book, which demonstrates that Sun Tzu values the geopolitical importance in the war. The geopolitical thinking of "Sun Tzu's Art of War" mainly manifests in three levels: geo-strategy, geography, and terrain. Geo-strategy level involves diplomatic, economic, psychological, and military fields and hence forms Sun Tzu's geo-political diplomacy strategy, geo-economic strategy, geo-psychological strategy, and geo-military strategy; geographical level discusses the relationship between geographical situation, national defense construction, and military thinking respectively; terrain's level explores the tactics of a variety of terrain. In general, the main connotation of Sun Tzu's geopolitical thinking appears in getting the "favorable geography" and winning the war. The connotations still have their values and provide a lot of inspirations in the 21st century.