Igneous series and distribution of the widespread Yanshanian magmatism, adakite, signification of I- and S-type granite, and the sources, tectonic settings and heat mechanism of granites are discussed in this paper. It is proposed that the tectonomagmatic discrimination diagrams, such as the diagram by Pearce et al . (1984), should be used with caution in distinguishing tectonic settings of granites. The depth of the source is considered to be the most important factor responsible for controlling the nature of granitoid rocks. Acording to the source depth, the authors have classified the granites into three types, viz., mantle-derived, lower-crust-derived, and middle-upper-crust-derived granites. The Yanshanian magmatism in eastern China resulted probably from underplated basaltic magmas generated from upwelling asthenospheric mantle in a continental crust extensional setting, and had nothing to do with the westward subduction of the Paleo-Pacific (or Izanagi) plate. Therefore, the Yanshanian magmatic rocks in eastern China do not belong to the circum-Pacific tectonic-magmatic belt. The reason, time and mechanism of delamination, however, need further detailed studies.