The PtCo-graphene/carbon dots/graphene (PtCo/GCG) electrocatalyst was prepared on a glassy carbon electrode via electrodeposition of PtCo nanoparticles onto the sandwich-structured graphene/carbon dots/graphene (GCG) composite. The obtained PtCo/GCG electrocatalyst has been characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy and also electrochemical measurements. Structure characterization indicates that the PtCo/GCG catalyst has good layered graphene morphology, with PtCo nanoparticles uniformly dispersed between the graphene layers. Electrochemical results indicate that PtCo/GCG catalyst has much better electrocatalytic activity and stability toward methanol oxidation when compared with PtCo/graphene and Pt catalysts. The improved performance is mainly owing to the embedding of carbon dots into the graphene layers, and the synergistic effect between Pt and Co nanoparticles. Carbon dots effectively adsorbed onto graphene layers, which increase the electrical conductivity, enhance the dispersion of PtCo nanoparticles, and subsequently enlarge the reactive surface area with more active sites.