A series of one-dimensional consolidation tests were performed on two types of clays dredged from Xiangmiao-Fushan section of Huaihe River with measured pore pressure at specimen base. Based on the experimental data, the difference between the degree of consolidation determined by settlement-time curve fitting method (the Casagrande method) and excess pore pressure dissipation method is investigated. The results show that excess pore pressure is not completely dissipated when the degree of consolidation determined by the Casagrande method reaches 100% and the remaining undissipated is about 10%~20% of the staged loading. Besides, the difference in settlement determined by the two different methods has a semi-logarithmic relationship with the vertical effective stress. In the end, the vacuum drainage preloading is taken as example to investigate the differential magnitude in settlement determined by the two different methods.