The consolidation coefficient is the important parameters for soft soil foundation to predict its consolidation settlement. At present, one-way compression test is mainly used to study consolidation process and consolidation coefficient of soft soil. For saturated soft soil in marsh, through triaxial shear test, the dissipation of pore water pressure and consolidation process can be observed during the course of soil sample drainage. This study got test result bellow through above triaxial test. Firstly, pore water pressure has hysteresis effect during the consolidation process, and the reason for this is analyzed. Secondly, consolidation degree in different consolidation time can be got according to the change of discharged water volume. Thirdly, according to Terzaghi consolidation theory, consolidation coefficients can be got under different consolidation pressures. Consolidation coefficient first increases with the increasing of consolidation degree, when consolidation degree is between 40% and 80%, saturated soft soil has larger consolidation coefficient, consolidation coefficient of saturated soft soil in marsh is between 2Ч10-4 cm2 / s and 10Ч10-4cm2 / s.