Grain size distribution of bulk loess-paleosol and quartz chemically extracted from the loess/paleosol shows that mean size of the bulk samples is always finer than that of the quartz. The original aeolian depositions have been modified to various degrees by post-depositional weathering and pedogenic processes. The grain size distribution of the isolated quartz should be close to that of the primary aeolian sediment because the chemical pretreatment excludes secondary produced minerals. Therefore, the grain size of the quartz may be considered to more clearly reflect the variations of winter monsoon intensity. Grain size distribution of bulk loess-paleosol and quartz chemically extracted from the loess / paleosol shows that mean size of the bulk samples is always finer than that of the quartz. The original aeolian depositions have been modified to various degrees by post-depositional weathering and The grain size distribution of the isolated quartz should be close to that of the primary aeolian sediment because of chemical pretreatment excludes secondary produced minerals. Therefore, the grain size of the quartz may be considered to be more clearly reflect the variations of winter monsoon intensity.