Granite in the Yunmeng mountains of Beijing is intrusive as a Mesozoic granite dome. Within the granite dome foliation is frequently observed and its traces are parallel with the boundary between granite and host rocks. The foliation development progressively strengthens from the core to edges, and the foliation on the SE side is stronger than that on the NW side. Deformation structures indicate that extensional tectonics at different crustal levels and in different directions are prevalent on the edges of the granite dome and its host rocks. The Hefangkou-Shuiyu "extension type" ductile shear zone characterizes its SE side. The indication of the shear shows a NW-SE normal shear movement. From a finite strain analysis, it is estimated that the shear displacement is over 10 km. The upper part of the shear zone is cut by the Hefangkou normal fault. Microstructures and quartz fabrics indicate that the deformation temperatures decrease from below upward in a direction perpendicular to the strike of the shear zone, which might be related to the cooling history of granite. On the other hand, the NW side of the granite dome is mainly manifested by a shallower-level normal fault and normal-strike slip fault.