The Nd-Pb isotope composition and source materials of the Cretaceous Quantou Group clastic sedimentary rocks and meta-granite in the Qing'an area,the Songliao Basin, are studied in this paper. The results suggest that the Cretaceous Quantou Group clastic sedimentary rocks and meta-granite are the product of clastic substances and their source materials consist of recirculated substance of the old crust. The source materials of the clastic sedimentary rocks and coarse-grained granite were derived mainly from the upper crust, while the fine-grained granite came primarily from the lower crust. The Pb isotope composition suggests that the clastic sedimentary rocks and coarse-grained granite are cognate products,but the fine-grained granite is different from either of them. The Nd isotope composition suggests that the physical circumstance and source materials of the Qing'an area are similar to those of the North China block, but different from those of the South China block.