TTG suite is an assemblage of three kinds of lithologies, namely the abbreviation of tonalite-trondhjemite-granodiorite. Although the TTG suite exists through the Earth history, it reaches the maximum scale during the Archean, consisting of the major part of primitive continental crust. TTG suite is named after petrological characteristics and most of them have similar geochemical features, i.e. Na-rich, high-aluminum (mean＞15%), low in Mg, Ni and Cr, LREE-enriched while HREE-depleted, High-Sr, low in Y and Yb and no evident Eu negative anomaly, that are similar with Adakites in the chemical features of rare elements. Most scholars believe TTG melt is derived from partial melting of metabasaltic protoliths while having little consensus on possible metamorphic phases of sources. Authors think it may not be constrained within a narrow range of P-T condition. As for the diagenetic environments, from the authors' humble opinion, it is more appropriate for us to take different geodynamic backgrounds throughout the Earth history into serious consideration thus obtaining relatively objective and trustworthy results. Therefore, the diagenetic environments of TTG before 3.8Ga might be related to non-subduction backgrounds; that of 3.8~1.9Ga might be related to multiple possibilities reflecting the episodic features of subduction; that of 1.9Ga-present might be more reasonable related only to subduction.