陳淳《北溪字義》雖是發揮朱熹《四書集注》的理學思想，卻不討論朱熹的「理氣」議題；這是否因為朱注《四書》中，本身就不論及理、氣的關係呢？還是陳淳本身的理氣觀，已對朱熹理氣論做了修正，而表現在《北溪字義》上呢？本論文以為：第一，陳淳雖繼承朱熹思想，然修改了朱熹「理先氣後」之說，而主張理氣為同層同質的融合統一存在。第二，陳淳如同朱熹「無極而太極」的主張，以無極只是形容太極的無方所形體，但卻又指出太極雖是理之極至者，更是理氣合一的「渾淪」，而非朱熹太極即理之論。由此可見，陳淳應自覺發現與朱熹理論上的不同處，故在《北溪字義》中無「氣」這一理學範疇。因此，本論文由陳淳「纔有氣，便有理」的理氣合一觀點，重新建立其理氣論的架構

Chen Chun inherited the Neo-Confucianism ideology of Zhu Xi, but Chen Chun did not discuss the ＂Li-Qi theory＂ of Zhu Xi's Neo-Confucianism ideology.The reason is whether there was no ＂Li-Qi theory＂ in Zhu Xi's book or the thought of Chen Chun was changed? This thesis held that there are two reasons as following: First, Chen Chun amended the theory of Zhu Xi. Chen Chun transformed theory of ＂Li first Qi＂ into the theory of ＂combination of Li and Qi＂. Second, Chen Chun and Zhu Xi both asserted that the ＂Wuji(無極)＂ is able to describe the invisibility of ＂Taiji(太極)＂, but the difference is Chen Chun asserted the combination of ＂Wuji＂ and ＂Taiji＂. According to the opinions mentioned above, Chen Chun should be conscious of the different theory between Chen Chun and Zhu Xi. Therefore, there was no discussion ＂Qi＂ in Chen Chun's ＂Pei-hsi Tzu-i(北溪字義)＂. Contrarily, Chen Chun re-established a new theory of ＂combination of Li and Qi＂