Abstract: This paper, by using reliability theory, Suggests a comprehensive probabilistic analysis on sett-lement,consolidation and differential stettlement for foundation treatment field testing site in Shen-Zhen Huang-Tian Airport The spatial variability and some uncertainties about the soil property constants were property considered and two kinds of probabilistic models on calculating settlement and consolidation for soft foundation treatment by sand drain and preloading method were deduced. The analysis results verified that the possible posterior differential sttlement will be less than the allowable value.