LA-ICP-MS zircon U-Pb ages and geochemical data of the Mesozoic bimodal volcanic rocks from Nenjiang in the Da Hinggan Mountains were studied in this paper. U-Pb ages of zircons show that the Mesozoic bimodal volcanic rocks were formed at the late stage of the Early Cretaceous (about 127.5 Ma). The Baiyingaolao Formation acidic volcanic rocks are composed of rhyolites and rhyolitic crystal clastic tuffs. The Meletu Formation basaltic volcanic rocks are composed of trachybasalt, basaltic andesite and basaltic trachyte. Geochemical studies suggest that the late Early Cretaceous volcanic rocks display a bimodal volcanic rock association. The Meletu volcanic rocks belong to alkaline series, have low silicon and are rich in alkalis. The chondrite-normalized REE patterns indicate that the volcanic rocks are enriched in light rare earth elements (LREE) with significant fractionation between HREE and LREE and week Eu anomalies. The trace element geochemistry is characterized by enrichment of large ionic lithophile elements (K, Rb, Ba) and depletion of high field strength elements (Nb, Ta). These characteristics indicate that the volcanic rocks originated from the remelting and fractionation of metasomatized enriched subcontinental lithospheric mantle, probably mixed with a small amount of crustal materials. The alkaline basalt series was formed under the condition of an intraplate setting, most likely continental rift. The Baiyingaolao volcanic rocks are rich in silicon and alkalis, poor in calcium and magnesium and have characteristic FeO^T/MgO ratio. The chondrite-normalized REE patterns indicate that the volcanic rocks are enriched in light rare earth elements (LREE) with significant fractionation between HREE and LREE and strong negative Eu anomalies. The trace element geochemistry is characterized by enrichment of large ionic lithophile elements (K, Rb) and LREE, and depletion of high field strength elements (Nb, Ta, P, Ti). The trace element geochemistry characteristics of rhyolites show an affinity with the A-type granite, suggesting that the volcanic rocks should have been formed in an extensional setting. These characteristics imply that the low-Sr rhyolitic magma originated from enriched mantle plume that intruded into the lower crust, and made it partially melted. The bimodal volcanic rocks were probably formed in an extensional setting. Combined with spatial and temporal distribution of the Mesozoic volcanic rocks in Northeast China, it is suggested that the formation of the late Early Cretaceous bimodal volcanic rocks might be attributed to subduction of the Paleo-Pacific plate beneath the Eurasian continent.