Abstract: In order to investigate the relationship between yielding stress of structures(k) and matrix suction(),intact samples from first palaeosol(S1) and fifth loess(L5)were taken from Jingyang, Shanxi Province. The specimens were prepared as 8groups with the expected moisture content from dry to saturated respectively. Based on high-pressure consolidation test,k under different moisture content were investigated, and the wetting soil-water characteristics curves(SWCC) is measured with filter paper method. The results suggest that with the matrix suction raise,k of S1 and L5 present a S model changes. When matrix suction less than a,k is in the lowly gentle stage of the S model. When matrix suction greater than r,k is in the highly gentle stage of the S model; as well as matrix suction between them,k have a quick increase as matrix suction increases. Gravity stress is pre-consolidation pressure, and discuss the change characteristics of structures strength with matrix suction in detail.