Western Hills of Beijing locates in the intersection part of Taihang and Yanshan tectonic belts, there were a series of Early Cretaceous volcano—sedimentary basins in northwest of Western Hills of Beijing, and preserved a set of volcanic rocks and clastic rocks, named by the Donglingtai formation which can be divided into four sections. Basin fills consist predominantly of alluvial fan, braided river, lacustrine and volcaniclstic deposits. The series of alluvial fan conglomerate were preserved in the lower part of first and second section of Donglingtai formation, respectively. Braided river deposits composed mainly of the upper layers of the second section. Lacustrine facies developed in the Yanhecheng basin, and along two border faults, the Yanhecheng fault and the Hengling—Yanhekou fault. Paleocurrent and gravel composion stastistics indicate that the Proterozoic Wumishan formation northeast of basins provided most deposits at first, after that mainly from the west area of basins, and the same period of volcanic gravels. The pyroclastic rocks of the bottom of first section zircon UPb age revealed the initial and inverive time of basin as 140.22Ma and 133.37Ma, respectively. Based on the characteristic of Basinmargin structure, filling process, the normal fault in Donglingtai formation, and evolution of regional geology, the northeast direction of Yanhecheng fault is thought to have played a critical role by leftlateral transtension, and created extensional stress along the southwestern Hengling—Yanhekou fault. The leftlateral transtension during the early stage of early Cretaceous may has played an important role in adjustment from compression to extension in late Mesozoic in eastern of North China.