Lateral-torsional coupled seismic response of sliding base-isolated structures under bi-axial ground excitations is carried out. The influence of eccentricity and torsional stiffness of the isolation layer is studied. It is shown that the influence of the stiffness eccentricity in the isolation layer is more remarkable than that of the mass eccentricity in the isolation layer. The torsional stiffness of the isolation layer has an impact on the displacement of the isolator, so the displacement of the isolator can be decreaseed by increasing the torsional stiffness of the isolation layer. When the isolator is placed symmetrically, the seismic response of the base-isolated structures can be controlled.