The standing-wave design was extended to achieve any desired split of mixtures containing three or more components in a single-ling and a tandem two-ring simulated moving bed (SMB). Mass-transfer effects were considered in the design for nonideal systems. The separation of a four-component mixture of glucose, Xylose, acetic acid and sulfuric acid was chosen to illustrate the design method. Rate-model simulations confirmed that the standing-wave design method could guarantee high purity and high yield. If all the components in a ternary mixture need to be recovered with high purity and high yield, the easier separation should be performed in the first ling of a tandem SMB to achieve the lowest desorbent consumption and the highest product concentration. If only the intermediate component needs to be recovered in high purity, one of the impurities should be allowed to distribute between the two product polls in the first ling to achieve a lower desorbent consumption and a higher product concentration. These strategies also apply to the separation of a mixture containing more than three components.