The deposition of platinum on the tungsten carbide (Pt/WC) have been achieved and proved with high stability, activity and CO-tolerance toward some reactions in experiments. Although a lot of experimental efforts have been focused on understanding the activity, stability and CO-tolerance of Pt/WC, the relevant theoretical works related to the CO-tolerance mechanism are still scarce. In current study, the adsorption and oxidation of CO on the Pt monolayer supported on WC(0001) surface (Pt-ML/WC(0001)) are investigated using density functional theory calculations. It is found that the oxidation of CO on Pt-ML/WC(0001) proceeds preferably along the Langmuir-Hinshelwood mechanism. The energy barrier of 1.06 eV for the rate-determining step of 0000 formation is almost equal to that (1.05 eV) for CO oxidation by atomic 0 on Pt(111), while the adsorption energy of 1.59 eV for CO on Pt-ML/WC(0001) is smaller than that on Pt(111) (1.85 eV), indicating that the high resistance to CO poisoning of Pt-ML/WC(0001) may originate from the weak interaction between them. To further improve the CO tolerance, some probable strategies are proposed based on the relevant kinetics results. The current results are helpful to understanding the origin of the highly resistant to CO poisoning of Pt-ML/WC(0001) and rationally designing catalysts to improve the CO oxidation activity. (C) 2016 Elsevier B.V. All rights reserved.