Abstract: The volcanic rocks of Manketouebo Formation in Xinlin area, northern Daxinganling Mountains are mainly composed of rhyolites, dacites and tuffs, while those of Baiyingaolao Formation mainly consist of rhyolites and tuffs. The zircon U-Pb dating results show they are formed in the Late Jurassic (154.5±0.68 Ma) and Early Cretaceous (121.12±0.5 Ma) respectively. Both are characterized by obvious fractionation of LREEs and HREEs with right-dipping REE patterns. The former, belonging to high-k calc alkaline-shoshonite series, has moderate negative Eu anomaly, with enrichment of LILEs (K, Rb, Ba and Sr) and LREEs and depletion of HFSEs (Nb, Ta, Ti and P). The latter, being high-k calc-alkaline series, features evident negative Eu anomaly, with enrichment of LILEs (K, Rb) and LREEs, obvious depletion of Ba and Sr and severe depletion in HFSEs(Nb, Ta and Ti). Combined with the geochemical characteristics and previous researches, it is believed that the Manketouebo volcanic rocks derived from crystal fractionation of basaltic magma in lower crust are related to the post-orogenic extensional environment after the closure of Mongolia-Okhotsk Ocean, and the Baiyingaolao volcanic rocks are formed by partial melting of amphibolites in lower crust and the extension induced by subduction of Pacific Plate.