Soil compaction may reduce the porosity, pore size and pore continuity of the soil and thus reduces air permeability, infiltration rate of water into the soil. Soil compaction also increases bulk density, mechanical strength and degradation of soil structure and thus leading to reduced crop yield and increased soil erosion and power requirements for tillage. One of the most important parameter in evaluating soil load capacity is pre-compression stress (? pc ) which is often used as a criterion for soil susceptibility to compaction.The ? pc is also used as soil compressive strength which is the single point that divides the compaction curve into two parts. When soil is subjected to stresses smaller than the ? pc , it deforms and recovers elastically. However at stresses greater than the ? pc , the soil deformation is irreversible. By limiting the mechanical stresses exerted on the soil below the ? pc , the risk of adverse changes in soil structure is prevented. One of major problems of agriculture in Iran is salt affected lands. Salinity problems are due to high water evaporation from the soil, low rainfall, topography and poor quality of irrigation water. These factors have caused many salty lands. Despite the large areas covered by saline soils in central Iran, there is little information on the soil sensitivity to compaction at different salinity levels and water contents. Therefore, the objectives of this research were (1) to study the effect of salinity and microstructure on compressibility and shear strength of soil under different soil water contents and (2) to determine the relationship between these two soil strength values. In this research, silty clay soils with EC valuess of 4, 9 and 13 (dS/m) were obtained from Rudasht region in Isfahan. The soil compressive properties were evaluated using plate sinkage test (PST) and confined compression test (CCT). Stress-sinkage and stress-strain curves were drawn for the PST and CCT, respectively. Soil shear strength parameters (cohesion, c and internal friction angle, ?) were measured by the direct shear box test. The effects of water contents (0.7PL, 0.9PL and 1.1PL; PL: platic limit), salinity levels (4, 9 and 13 dS/m) and two soil microstructures (remoulded and undisturbed) on pre-compression stress and shear strength were studied using a factorial experiment in a randomized complete design with three replications. Results showed that in PST, the maximum and minimum values of ? pc were obtained with Casagrande method and maximum curvature methods, respectively. In CCT, the maximum values of ? pc were obtained with Casagrande method and the minimum values of ? pc were obtained with intersection of virgin compression line (VCL) and x-axis. By increasing salinity level, and decreasing soil water content, and changing soil structure from remoulded to undisturbed the ? pc increased in both PST and CCT. However, increasing salinity level and changing soil structure from remoulded to undisturbed, led to a decrease in compression index (C c ). With increasing soil salinity, soil cohecion and internal friction angle reduced, but the changes in soil structure from remoulded to undisturbed, increased these parameters. Internal friction angle increased with increasing soil water content. Increasing soil salinity led to a decrease in estimated soil shear strength at its pre-compression stress point.