顧炎武「經學即理學」 是了解明清之際學術變化的重要線索。本文先整理前人的說法，指出學者對主要從「反理學」、「內在理路」、「經世致用」三種不同的角度來說明顧炎武提出此說的動機。其次，再從顧炎武對經學及理學的意見作一探討，說明顧炎武提倡經學之主因在於經世，而研究經典的方法強調探求聖人著作之本意；對理學則多有批判，並將理學中抽象的議題落實於人事之上。顧炎武治學實深受朱子的影響，然而其強烈的經世思想，使他對朱子之學有所轉化，故在學術上有不同的面貌。顧炎武「經學即理學」的意見雖非首倡，但他全力從事經學研究，並將經學與經世相結合，促使學術風氣漸漸轉變，而對清代學術產生了深遠的影響。

To understand the scholastic diversion between the Ming and Qing dynasty, Gu Yanwu's “Jingxue Ji Lixue” served as an important indictor. In the essay, we first pointed out three kinds of explanations of his thoughts: Anti-Neo-Confucianism, inner logic, and practicalism. Next, we discussed about Gu Yanwu's views on the study of the classics and the Neo Confucianism. He advocated studying the classics to manage the world in an orderly manner and placed emphasis on discovering the authors' real intention of these classics. He criticized Neo-Confucians for their vague ideologies and when discussing the same issues, he usually gave practical definitions to replace the abstract ones. Gu Yanwu's thoughts were influenced by Zhu Xi. However, because he had a different purpose, transformed Zhu Xi's theory. As a result, they proceeded in opposite directions. Although Gu Yanwu was not the first to suggest “Jingxue Ji Lixue”, he devoted himself to the study of classics, and combined the study of classics with practicalism. His efforts gradually changed the scholastic atmosphere and greatly influenced the study of the classics in the Qing dynasty.