In the mid-nineteenth century, Western industrialized countries forced China and Japan to abandon their isolationist policies and be incorporated into the international trade framework to expand their markets. However, since the two countries played passive roles, they called for language reform by themselves to resolve the unequal situation. The vernacular movement, which is rising in both China and Japan, has many similarities because of the similar social and cultural background. Although Chinese and Japanese languages are different, there are many differences between the movements. Consequently, the significance of comparative studies on the Chinese and Japanese vernacular movements has attracted the attention of researchers. However, most studies restrict the Chinese vernacular movement to the reform of the new culture movement in 1919 and rarely analyze the vernacular movement in the late Qing Dynasty and the 1930s. This paper compares the vernacular movements of China and Japan based on the specific circumstances of the movements. Moreover, the paper summarizes the role of vernacular movements in China and Japan’s language reform according to the relationship analysis between the vernacular movement and the spelling reform.