Abstract: The optically stimulated luminescence (OSL) dating method, a technique closely related to TL, which is developing extensively in recent years, determines the time since the sediment was last exposed to sunlight. A monochromatic light is used in OSL dating, instead of heat, to excite electrons (or holes) from thermally stable light sensitive traps on a geological time scale. The luminescence obtained from feldspar grains when they are stimulated by infrared photons, is termed infrared stimulated luminescence (IRSL). The OSL dating technique offers several major advantages over conventional TL dating. Not only is the residual signal following deposition lower for OSL, but also much improved signal to noise ratios, greater precision and speed of sample measurement, and some degree of mineral selectivity. IRSL dating of sediments from Quaternary tectonic terraces in Yumen, Gansu Province, demonstrates that the formation periods of terraces of Shiyouhe, Baiyanghe and Dahuanggou are at about 90, 70, 44, 29, 20, 13 and 5.6ka B.P, respectively, which shows agreement with field observation.