Salt damage caused by the complex interaction between water and salt in the heritages is the main factor that deteriorates the materials and destroys the historical information of the relics. The influence of environmental conditions, especially humidity, on salt damage of heritages has been emphasized by many researches. In this study, the water-salt migration characteristics in soil columns under different humidity were studied by laboratory tests. First, water vapor adsorption test was carried out to investigate the soil samples adsorption capability in 6 relative humidity conditions (RH11%, RH23%, RH43%, RH60%, RH75%). There is a linear relation between relative humidity and water vapor absorbed by soil, and the water vapor adsorption curves of samples can be well described by first-order exponential attenuation equation. Second, the water content and conductivity distribution within samples (hygroscopic and non-hygroscopic samples respectively) were investigated after capillary migration tests using 4 types of saline solutions (0.2 mol/L NaCl, 0.2 mol/L Na2SO4, 0.2 mol/L NaCl Na2SO4 mixed solution and distilled water). Results show that high conductivity appears on the top of most samples, and the values have a correlation with type of capillary migration fluid: NaCl > Na2SO4 > NaCl-Na2SO4 > H2O. In addition, the distribution of water content and conductivity becomes complicated under different relative humidity conditions.