This paper provides the differentiated elements of Geng Rhyme Groups (梗攝) in historical literatures from Jin Dynasty to Tang Dynasty by analyzing the Fanqie (反切) and the phonics materials noted by various commentators in Annotations of the Chinese Classics. By using modern Chinese dialects and extraterritorial translations as references, it can be seen that in the system of the Geng Rhyme Groups of the North, the vowels of Divisions Ⅱ and Ⅲ were lower whilst those of Division Ⅳ were higher. The vowels in the Southern Dynasty's the vowels in the Geng Rhyme Groups were low vowels. However, the systems of rhymes had been differentiated and combined after the integration of the North and the South, and those from the same system in the Geng Rhyme Groups could, as a result, be replaced by one another. This had made the Geng Rhyme Groups less distinguishable in the rhyme of poetry. Since Tang Dynasty, the pronunciation overall in the Geng Rhyme Groups had had the tendency of being high. On the one hand, Qing Rhyme (清韻) vowels were higher and integrated with Qing Rhyme (青韻), but on the other hand, those of Division III of the Geng Rhyme Groups had become an integrated system while those of Division III of Qing Rhyme (清) and Qing (青) Rhyme were still separated into two. In the history of phonics' transformation, the differentiation in the same period of time can, therefore, be presented here.