The invention belongs to the technical field of preparing oxalate in coal to ethylene glycol, aiming at providing a preparation process for nanocatalysts with (111) crystal facet exposed and a process for vapor-phase CO oxidative coupling to oxalate. The nanocatalysts with (111) crystal facet exposed comprise carrier, active component and promoter on the carrier, wherein, in term of the weight of the carrier, the active component accounts for 0.05-2% of the weight of the carrier, the weight percentage of metal elements in the promoter is 20% or less. The nanocatalysts with (111) crystal facet exposed are prepared by the nanometals in situ supporting process. The preparation process is simple in procedure, has low energy consumption and can precisely control the size and exposed crystal facet of the active component nanoparticles. The obtained nanocatalysts with (111) crystal facet exposed are highly active for vapor-phase CO oxidative coupling to oxalate at a lower loading of noble metal.
