The heave frequencies of the floating VAWT were equal to the wave frequencies. The floating VAWT S-2 had better motion performance its heave and pitch motions were all small. It was observed that the amplitudes of the heave and pitch motions of the floating VAWT depend on the wave loads the mean values of the heave and pitch motions depend on the aerodynamic loads. The motion performances of the two floating VAWTs, S-1 (the VAWT supported by FS-1) and S-2 (the VAWT supported by FS-2), were analyzed and compared. Two sets of foundation parameters (FS-1 and FS-2) were selected to support the 5 MW Darrieus wind turbine. The results show that radius of the buoyancy tank, radius of the upper mechanical tank, interval of the center of gravity and center of buoyancy, and height of the upper mechanical tank have important effects on the heave and pitch motions of the foundation. The effects of changes in foundation structural parameters on its motions were evaluated. This paper studies the dynamic characteristic of the truss Spar-type floating foundation used to support the offshore vertical-axis wind turbine (VAWT).