The widespread Mesozoic magmatic activities in the Yanshan area occurred in four stages and eight epochs. This paper summarizes the basic types, occurrences, distribution and petrochemical features of igneous rocks, discusses the tectonic environments for the formation of volcanic and intrusive rocks and expounds the magmatic activities brought about by tectonic movements and process of intracontinental orogenesis. The authors emphasize that multi-stage magmatic activities are the direct products of the orogenic movements. The tectonic environments indicated by the igneous rock series and petrochemical features suggest that the Yanshan area should be an intracontinental orogenic belt during the Mesozoic and its major feature of tectonic evolution is the development of reversal structure.