Abstract: Loess is a kind of special soil with high water sensitivity, and the loess with natural water content can keep high and steep stable for a long time. However, when water comes, it shows strong water sensitivity of disintegration, dissolution, liquefaction, creep, and sliding. Research on the water sensitivity of loess and its special-temporal distribution has a practical significance to guide the engineering constructions in the unsaturated loess area. Based on the theory of unsaturated loess, the concept of suction stress is introduced to explain the water sensitivity of loess. The essence of water sensitivity is, the suction stress decreases with the increase of water content, and the different deformation behaviors will occur under different boundary conditions. Loess samples have been collected along sections from west to east and north to south of the Loess Plateau for obtaining their curves of SWCC and SSCC with TRIM technique. The results show that, these curves change similarly and show three distinct sections under both drying and wetting conditions. The water sensitivity of loess varies regularly with sedimentary dates and locations in the Loess Plateau. From west to east, north to south, the water sensitivity of loess is increasing; In terms of time, the water sensitivity of loess is increasing from old to new sedimentary age.