The invention belongs to the technical field of 
organic compound preparation, and discloses 
ioversol and a synthesis method thereof. The chemical name of 
ioversol is N,N'-bis(2,3-dihydroxypropyl)-5-[N-(2-hydroxyethyl)-hydroxyacetamido]-2,4,6-triiodo-1,3-benzenedicarboxamide. 5-hydroxyacetylamino-N,N'-bis-(2,3-dihydroxypropyl)-2,4,6-triiodo-1,3-benzenedicarboxamide and an 
alkylation agent carry outalkylation reactions under an alkaline condition to generate 
ioversol. Bromoethanol and 
sodium hydroxide are taken as reagents; glycol and 
anhydrous ethanol are taken as a mixed 
solvent, in the absence of water, a substrate can be well dissolved; the 
hydrolysis of the 
alkylation agent is avoided, the 
raw material loss is largely reduced, the 
utilization rate is increased, the reaction yield is increased, and the cost is reduced. At the same time, dangerous and toxic reagents such as chloroethanol, 
ethylene oxide, and the like are not used, the safety 
hazard is reduced, the damage to 
human body is reduced, and the stability of industrial production is guaranteed.