The typical loess profile at Potou on the central Chinese loess plateau was sampled at 3-10 cm intervals. All samples were measured for magnetic susceptibility and grain size. The magnetic susceptibility and percentage of the >30 um grain size fraction were used as indicators of summer and winter monsoon strengths respectively, and on the basis of a new reliable time scale, a time series of paleomonsoonal climate variation in East Asia was set up. Spectral analysis for the new time series presents the 100 ka, 41 ka and 23 ka cycles of variations of the orbital elements of the Earth movement. Meanwhile, other cycles such as 80 ka, 56 ka and 30 ka were also recorded in the loess-paleosol sequences unambiguously. The cycles of paleomonsoonal variations during the Quaternary evolved with time, and those of winter and summer monsoons were different in some stages. The variations of the orbital elements of the Earth were not the only dominant factor which triggered cycles of the East Asian monsoonal changes during the Pleistocene, and other factors within the monsoonal system were also important. In addition, the cycles of summer and winter monsoon variations during the past 2500 ka and relationships between them are multimod-el.