Influence of ozonolysis on group and elementary composition of vacuum gas oil has been studied. It was determined that during ozonolysis the most change of group hydrocarbon composition has been noticed: difference in content of mono- and polycyclic aromatic hydrocarbons is increased three times (12.4 %). Also the significant growth of asphalt-resin substances: from 0.78 up to 1.42 mas. % was noticed. Subjected to adsorption purification ozonizated vacuum gas oil is characterized by significant decrease of nitrogen containing and resin-asphalten compounds: up to 0.1 and 0.51% correspondingly. It is shown that on distribution of elementary both conducting of ozonolysis and subsequent after it adsorption purification exercise influence: is accompanied by significant growth, then lay decrease of oxygen content (from 2 up to 5.1 and 3.5 mas. %) and essential decrease content of sulphure (from 1.7 up to 0.26 mas. %).