Abstract: The consolidated undrained triaxial shear tests and coupled axial-torsional cyclic shear tests are conducted using the marine fine-grained sand to study the correlation between the critical state parameter and the liquefaction characteristics based on the critical state theory. The tests results show a linear correlation between the critical void ratio and the normalized effective normal stress. The results of the coupled axial-torsional cyclic shear tests show that the cycle number for liquefaction, N_L, decreases with the increasing state parameter, ψ, for a certain cyclic resistance ratio. Finally, an exponential function for expressing the relationship between N_L and ψ is proposed.