The invention relates to a liquid hydrocarbon mercaptan removal technique capable of deeply removing total sulfur, in particular to a sweetening technique for liquefied gas in an oil refinery. The oil refining liquid hydrocarbon refers to components of liquefied gas and light gasoline, wherein the liquefied gas is a raw material for producing MTBE, and the light gasoline is a component for producing high-cleanness gasoline. In order to solve the problem of high total sulfur in the oil refining MTBE and the light gasoline, according to the shape and the distribution rule of sulfocompounds in the liquid hydrocarbon, processes such as functional reinforcement of a recycle solvent, three-phase mixed reinforced regeneration, regenerated catalyst and extractant separation and recycle solvent deoxidization and the like are adopted in the conventional process of liquid hydrocarbon extraction, oxidization and mercaptan removal, so the technical effects of reinforcing the mercaptan removal depth, improving carbonyl sulfide removal rate, and avoiding forming disulphide in the extracting, saving energy and reducing emission and the like are achieved. Thus, the liquid hydrocarbon can be deeply desulfurated, the problem of high total sulfur in the oil refining MTBE and the light gasoline is solved and the slag discharging quantity in the conventional process is greatly reduced.