Abstract: The grain size distribution of loess is considered as aI1 important proxy index describing the East Asia paleomonsoon climatic variations recorded by Chinese loess deposits during the Quaternary. In this paper, the grain size of 1580 samples in the Luochuan loess-paleosol sequence has been measured. Based on the fractal theory, the fractal dimension (D) of the grain-size has been calculated. Results show that the grain-size distribution has fractal characteristics. The D values in loess are between 2.16 arxl 2.51, with al1 average of 2.32, a little lower than those in paleosols which are 2.23-2.51，with an average of 2.41. Similar to other climatic indicators, the D values are strictly related to the loess-paleosol cycles of the sequence, suggesting that this parameter could also serve as an index for monsoon climatic changes in the Loess Plateau. The D values show that the East Asian monsoon has gradually strengthened since 2.50MaB. P. with the amplitude of climatic fluctuations increasing and the frequency reducing. The monsoon strength is weaker during the Early Pleistocene and displays high-frequency，low-amplitude changes with 20-40 kyr cycles. While during the Late pleistocene the monsoon is stronger and shows low frequency, high-amplitude changes with 100 kycrycle, From this point of view，the D value could be a new indicator for evaluating the strength of the strength of the East Asia monsoon circulation and indicating the evolution of environment in which loess and paleosols formed.