Abstract: The gaseous phase synthesis of diethyl oxalate and oxalic acid with CO was an important project of C1 chemical technology because CO source was abundant and its oxygen content was 57%. This process is a new green chemical technology. The catalysts for the titled reaction were prepared with impregnation method. The performance of Pd-Me/Al2O3 catalysts for the synthesis of diethyl oxalate from CO in gaseous phase were optimized and evaluated in a fixed-bed flow reactor with industrial feed gases that includes oxygen, H2O, and sulfur. The influences of Pd loading, the molar ratio of Pd to promoter Fe and the type of Al2O3 supports on the performance of the catalysts were investigated. It was found that the performance of the catalyst was appropriate when the Pd loading was 1%～5%, Pd/Fe molar ratio was 0.2～2.0 and the supports were bar α-Al2O3 carriers. The yield of diethyl oxalate was more than 900 g/L·h－1 with the conversion of CO over 63% and the selectivity to diethyl oxalate more than 95%, and the catalysts was stable.