Objectives:There are a set of intermediate—acidic intrusions in Shibazhan—Hanjiayuan area, Great Hinggan Mountains. This article focus on the chronology of monzodiorite, geochemical characteristics of monzodiorite and monzonitic granite, and their geological significance.Methods: Detailed geological survey, LAICPMS zircon UPb dating of monzodiorite, and whole rock geochemical analysis of monzodiorite and monzonitic granite.Results:LAICPMS zircon UPb dating of monzodiorite yielded a weighted mean age of 512.4±3.5Ma, revealing that it was a product of the early Paleozoic magmatism. Intermediate—acidic intrusions belong to metaluminous (A/CNK=0.77~1.04), calcalkaline to highK calcalkaline series based on the geochemical analysis results. ∑REE change between 69.51×10-6 and 275.83×10-6 with (La/Yb)N ranging from 9.11 to 26.64. REE patterns are characterized by enriched in LREE and relatively depleted HREE with a moderate Eu anomaly (δEu =0.90~1.35). Trace elements characteristics show that the early Paleozoic intrusions distinctly enriched in LILE (Ba, Sr) and prominently depleted in HFSE (Nb, Ta, Ti).Conclusions:Combining achievements of predecessors with this study, we concluded that intermediate—acidic intrusions generated from an active continental margin or island arc environment, and it was a product of Salair orogeny, which related to PaleoAsian ocean closing.