The study of Paleoproterozoic meta-mafic-ultramafic rocks in the North Liaohe Group of the Liao-Ji orogenic belt in the North China Craton provides critical evidence for understanding regional tectonic evolution. Through detailed field investigations, petrographic observations, and systematic geochemical analyses, combined with previous research findings, this study yields new insights into the petrogenesis and tectonic setting of these rocks. It also presents a preliminary discussion on the intrinsic genetic relationship between the geodynamic mechanism of the Liao-Ji orogen and the source of Ni-Co elements. Based on previous data, the protoliths of the meta-mafic-ultramafic rocks have a peak emplacement age of ~2 152 Ma and underwent regional metamorphism at approximately 1 882 Ma. Geochemical results indicate that the meta-ultramafic rocks are hornblende-chlorite schists with a cumulate origin. Their LREE enrichment and Nb-Ta-Ti depletion characteristics suggest that the primary magma likely experienced metasomatism by subduction-related fluids. The protoliths of the meta-mafic rocks are all subalkaline tholeiitic basalts, which can be classified into two types. The first type exhibits geochemical features similar to MORB, originating from a depleted asthenospheric mantle source with limited fluid metasomatism. Zircon Hf isotopes from this type provide direct evidence for Paleoproterozoic juvenile crustal growth events in the Liao-Ji orogen. The second type of meta-mafic rock shows significant LREE enrichment and Nb-Ta-Ti negative anomalies, indicating that their primary magmas were derived from an enriched lithospheric mantle source that was intensely metasomatized by subduction fluids.Based on the petrogenetic mechanisms and source characteristics of the meta-mafic-ultramafic rocks, this study proposes that they formed in a back-arc basin tectonic setting. The two types of meta-mafic rocks respectively record the complete evolutionary process of the back-arc basin from initial extension (enriched component) to maximum spreading (depleted component). Ni-Co mineralization is closely related to this evolutionary process: back-arc extension facilitated mantle melting and extraction of Ni-Co elements; magmatic underplating and cumulate processes achieved pre-enrichment; the addition of crustal sulfur triggered sulfide melt segregation; and the final collisional orogeny led to the extraordinary enrichment and formation of the ore deposits.