Abstract: The MgO support was first synthesized by the solution method, with which the Pd/MgO nanocatalyst was then prepared by the impregnation method. The structure and performance of prepared catalyst were characterized by XRD, CO₂-TPD, BET, TG, SEM, TEM and catalytic evaluation device. The research result shows that the synthesized MgO support consists of uniform nanosheets and strong Lewis basic sites. The active Pd nanoparticles of Pd/MgO catalyst are highly dispersed on the surface of MgO support with small and homogeneous size. Moreover, the Pd/MgO nanocatalyst with a low Pd loading (0.5%) exhibits an excellent catalytic performance with 65% CO conversion, 96% selectivity to DMO and more than 100 h on stream at 130 ℃. for CO oxidative coupling to dimethyl oxalate, much higher than industrial catalyst (Pd/α-Al₂O₃), which has a good prospect of industrial application.