A comprehensive summary of the definition, mode of occurrence and remaining problems in the studies of C-type adakitic rocks is given in this paper for better understanding the implications of C-type adakite rocks in East China. It is pointed out that C-type adakitic rocks are high-K calc-alkaline and are likely derived from partial melting of intermediate- to high-K meta-andesitic-basaltic rocks under the high pressure condition. Unlike things of O-type adakite, the origin, source rocks and partial melting processes of C-type adakite remain unclear and hence more experimental work may have to be involved in future work.