A series of ZnO samples with different morphologies were synthesized by controlled preparation methods and processes,and employed as catalysts for the synthesis of diethyl oxalate (DEO) from dimethyl oxalate (DMO) and ethanol by transesterification route. The structure-activitySrelationships of this transesterification reaction over ZnO were systematically discussed with the help of XRD, N₂Sphysisorption, XPS, SEM and CO₂-TPD techniques. It was found that the catalytic activity of ZnO catalysts in the transesterification of DMO with ethanol is closely related to the ZnO morphologies. Among them, the flower-like ZnO-f is found to be the most active catalyst, and the DMO conversion over ZnO-f can reach 99.8 % with the selectivity to DEO of 75.8 % under the optimal conditions. The DMO conversion and DEO selectivity decrease from 99.1% and 68.2% to 93.9 % and 24.7 % after four cycles, respectively. This catalystSdeactivation can be ascribed to the presence of Zn(OH)₂ phase. Kinetic studies showed that the transesterification of DMO with ethanol over ZnO-f catalystSfollowsSfirst-orderSreaction with activation energy of 35.7 kJ/mol, and the abundant medium and strong basic sites over ZnO-f is responsible for its excellent catalytic activity in the transesterification reaction of the DMO reaction with ethanol.