An all-electron scalar relativistic calculations on AunCO (n = 1 - 10) clusters have been performed by using density functional theory with the generalized gradient approximation at the PW91 level. Our results reveal that all AunCO clusters prefer to keep the planar structures like pure Au-n cluster and the Aun structures in all AunCO clusters are only changed slightly. The carbon monoxide molecule prefers to occupy the on-top and single fold coordination site and small gold cluster would like to bond with carbon. The adsorptions in AuCO, Au6CO, Au9CO and Au10CO clusters are relatively weaker than the adsorptions in other AunCO clusters. After adsorption of carbon monoxide, the Au-Au interaction is strengthened and the C-O interaction is weakened. The VIPs, HLGs, HOMO and LUMO energy levels for AunCO clusters have obvious odd-even oscillation. The even- numbered AunCO cluster is relatively more stable than the adjacent odd-numbered AunCO cluster electronically and chemically. The odd-even alteration of magnetic moments is observed in AunCO (n = 1- 10) clusters and may be served as the material with tunable code capacity of "0'' and "1'' by adsorbing carbon monoxide molecule onto odd or even-numbered gold cluster.