A summary of the recently obtained zircon U-Pb or Rb-Sr ages of the Paleozoic-Early Mesozoic intrusive rocks in the Siziwangqi area indicates that at least four stages of magmatism including Cambrian to Ordovician, Carboniferous to Early Permian, Middle to Late Permian, Triassic occurred during the Paleozoic to Early Mesozoic period. The main components of the Cambrian to Ordovician intrusive are diorite and quarta diorite. The Carboniferous to Early Permian intrusive rocks consist mainly of gabbro, diorite and quarta diorite. Rocks from Middle to Late Permian intrusive suite are composed mainly of granodiorite, monzogranite, syenogranite with some hornblende-syenite. The main components of the Triassic intrusive are muscovite granite, monzogranite, and alkaline rocks. Compared with the Cambrian to Ordovician, Carboniferous to Early Permian, the Middle to Late Permian and Triassic intrusive rocks show much more extensive distribution. The wide distribution of the Paleozoic-Early Mesozoic intrusive rocks indicates a very complex tectonomagmatic history of the Siziwangqi area during the Paleozoic-Early Mesozoic period. The Cambrian to Ordovician and Carboniferous to Early Permian rocks are probably related to the subduction of the Paleo-Asian Ocean. The Middle to Late Permian rocks are interpreted as collision between North China Craton and Siberia plate. The Triassic intrusive rocks might have resulted from post –collisional lithospheric extension after final collision, represented the ending of orogeny.