In this paper, the liquefaction potential of medium dense and dense sand layers was studied by performing constant volume (undrained) cyclic simple shear tests using cyclic simple shear apparatus. Strain-controlled approach was adopted. The liquefaction potential of two layers of a silty sand soil profile consisting of surface medium dense layer and underlying dense sand layers were studied. A medium dense sand surface layer exhibited flow type total liquefaction in cyclic loading in few cycles after initial liquefaction. An underlying dense sand base layer showed initial liquefaction in relatively more number of cycles and then cyclic mobility due to which pore pressure increases and decreases with cycles that is the characteristics of dense sand. The pore pressure increase and decrease is directly related to decrease and increase of effective stress.