<p>Riedel shear system, which consists of some different oriented faults and derivative structures, is an important pattern of tectonic activity and stress regulation, which has been widely applied to the interpretation of intracontinental deformation. The Laolongwan Basin, located in the western Haiyuan fault zone at the northeastern Tibetan Plateau, is a key area to study the Cenozoic intracontinental deformation in the northeastern plateau, which formed a complex active fault system during the Cenozoic. However, the activity of these faults and their kinematic mechanism remain unclear. In this contribution, based on detailed structural interpretation of remote sensing image, field observations and OSL dating analysis, we propose a Riedel Shear model of active fault system in the Laolongwan Basin. Our observations show that this active fault system consist of four major faults, including the left strike-slip Hasi Shan fault and Zihong Shan fault with thrusting characteristics, the Southern Zihong Shan thrust fault and the Mijia Shan normal fault. The fault offset and OSL dating analyses suggest that the left-lateral slip rate of the Hasi Shan fault is ~2.60–3.01 mm/a since ca. 15 ka, whereas the Zihong Shan fault is ~1.10–1.13 mm/a since ca. 14 ka. Fault-slip vectors analyses indicate that the active fault system related to the Riedel Shear in the Laolongwan Basin was controlled by the regional ENE-WSW compressive stress. This compression also caused the significant left-lateral strike-slip movement along the Haiyuan fault zone at the same time, which might result from the northeastward continuous expanding of the Tibetan Plateau during the Late Cenozoic.</p>