Regarding the issues that when “yan” (眼) and “yanjing” (眼睛) began to indicate the eyes sememe, when “yan” (眼) and “mu” (目) had no distinctions in meaning, and when “yan” (眼) began to replace “mu” (目), different scholars have put forward different views. This paper suggests that “yan” (眼) beginning to indicate the eyes sememe should be during the Warring States Period. “Yanjing” (眼睛) indicating eyes sememe was first found in the Han Dynasty. The year that began to see no distinction in meaning between “yan” (眼) and “mu” (目) should be after the Song Dynasty and the Yuan Dynasty. “Yan” (眼) replacing “mu” (目) in oral Chinese language should begin from the Sui Dynasty and the Tang Dynasty.