Based on the basic structural motif of the icosahedral symmetric Co₅₅ cluster, the interaction between the Co-Mo clusters with a Mo atom at different substituting sites and single-walled carbon nanotubes with different chiralities ((10, 0) and (5, 5)) was studied by density functional theory calculations. The results show that the interaction between the system of Co-Mo mixed cluster and single-walled carbon nanotubes is strongly correlated with the location of the doped Mo atom in cluster and the chirality of the single-walled carbon nanotube. Compared with pure Co₅₅ clusters, Mo atom doped clusters have obvious enhanced structural control effect on single-walled carbon nanotubes, which has enlightenment for the controllable synthesis of single-walled carbon nanotubes.