Abstract: The widening project of highways on soft soil foundation faces great challenges. It is necessary to evaluate the engineering characteristics of the new and old foundation soils comprehensively. The traditional methods in laboratory cause disturbance to the soils, which is long and costly. As a new in-situ testing technology, CPTU, can be used to obtain parameters precisely and continuously including cone tip resistance, sidewall friction and pore water pressure. The multi-functional CPTU technology is used to test the new and old foundation soils of the Beijing-Shanghai Expressway. Based on the bearing capacity theory and the cavity expansion theory, the parameters of the old and new foundation soils are interpreted, such as the stress history, deformation and consolidation. It’s found that the distribution, thickness and depth of soft soil layer can be more determined accurately. In addition, the above-mentioned important engineering parameters can be provided as the scientific evidences for the prediction of differential settlement of old roadbed and the design and construction of subgrade splicing.