Taking a twinbox girder bridge with a slot width ratio of 20% as an example, the control effects of upward vertical central stabilizers (UVCS) and downward vertical central stabilizers (DVCS) on the bridge were investigated using CFD simulation and a series of wind tunnel tests, respectively. The results show that the amplitudes of heaving vortexinduced vibration(VIV) responses first increase and then decrease with the height increase of vertical central stabilizers, in which the amplitudes of heaving VIV responses for the UVCS with 0.4h/H and the DVCS with 0.2h/H were the smallest. The amplitudes of torsional VIV responses were enhanced by installing the UVCS while the DVCS are helpful to decrease the torsional responses. In addition, the results of the CFD numerical simulation show that VCS change the motion mode of vortex structures in the slotting and the pressure zones on the upper and bottom surface of the leeward side girder. It is found that the optimal control effective on the VIV performance is the DVCS with 0.2h/H, whereas the UVCS with 0.8h/H has the worst effective of all cases.