Objectives: The magmatic source, forming environment and tectonic setting were revealed by the age and geochemical characteristics of granite. Recently, during the geological survey and related scientific research work in the Shibanjing area of Inner Mongolia, we identified a set of Middle Devonian intermediate—acidic intrusive complexes in the Shibanjing area. In this study, we discuss the petrogenesis, forming environment and tectonic setting of intemediate—acidic intrusive complexes.Methods: Based on field work, through the microscope, zircon UPb dating, wholerock major and trace element geochemistry were carried out.Results: The results show that the finegrained augite diorite, mediumgrained granodiorite, medium to finegrained granodiorite and mediumgrained biotite monzogranite formed in the Middle Devonian(385~380 Ma), and they have homologous magma evolution characteristics. The finegrained pyroxenite diorite belongs to the calcalkaline, sodic, peraluminous series. The medium grained granodiorite, medium to finegrained granodiorite and mediumgrained biotite monzogranite characterized by the highK calcalkaline to calcalkaline, sodic, metaluminous—peraluminous series.Conclusions: The parent magma has been considered to be connected with the mantle wedge was metasomatized by the subducted plate fluid, and the partial melting of the mantle wedge forms basalt magma. The basalt magma underplating during the partial melting of lower crust. In the process, it is accompanied by the crystallization and differentiation of magma. The Middle Devonian intermediate—acidic intrusive complexes have the characteristics of type I granite, and it is volcanic arc environment formed in the background of the Oceanic island arc, the diagenetic environment may belongs to the southward subduction under the background of the Xiaohuangshan Ocean.