In order to investigate the influence of supporting column arrangement on the water-sediment separation performance of the vortex settling basin (VSB), laboratory tests were carried out on the VSBs with two rows of supporting columns which were arranged differently including side-by-side arrangement and staggered arrangement under different inlet flows and sediment concentrations. The results showed that the peak of silt and sand ripple on the VSB suspension deflector, the curvature and depth of bottom silt gully were the largest when there were no columns, followed by the side-by-side column arrangement, and the staggered arrangement produced the smallest values. Compared with no columns, the water consumption rate of side-by-side arrangement increased by 4.01% to the maximum, and that of the staggered arrangement increased by 4.25%. The installment of the columns reduced the tangential flow rate, spiral strength and secondary flow intensity and range of the VSB, with a stronger reducing effect seen in staggered arrangement. However, the indoor sediment mass of side-by-side arrangement was 3.10%-4.76% less than that of staggered arrangement, and the sediment discharge rate of its bottom hole was 0.90%-1.23% higher. Therefore, side-by-side arrangement is recommended in engineering design because the floor silting amount, bottom hole discharge rate, total sediment removal rate and sand discharge water consumption rate of this arrangement are close to those of no columns. The research results are expected to provide a reference for the optimal design of the suspension deflector support system of VSBs.