NOVELTY - Isobutane preparation system comprises extractive distillation column, alkane water washing tower, stripping column, olefin washing tower, solvent recovery column, hydrogenation reactor, hydrogenation material adding and discharging heat exchanger, hydrogenation feed heater, hydrogenation separation means, dehydration tower, and isobutane finished tower. The top of the extractive distillation column is connected to alkane water washing tower, and the bottom of the extractive distillation column is connected to stripping column.    USE - Used as an isobutane preparation system.    ADVANTAGE - The device achieves economic benefit.    DETAILED DESCRIPTION - Isobutane preparation system comprises extractive distillation column, alkane water washing tower, stripping column, olefin washing tower, solvent recovery column, hydrogenation reactor, hydrogenation material adding and discharging heat exchanger, hydrogenation feed heater, hydrogenation separation means, dehydration tower, and isobutane finished tower. The top of the extractive distillation column is connected to alkane water washing tower, and the bottom of the extractive distillation column is connected to stripping column. The top of the stripping column is connected to olefin washing tower, andt hge bottom of the stripping column is connected to extractive distillation column. The top of the alkane water washing tower is connected to hydrogenation material adding and discharging heat exchanger, and the outlet of the hydrogenation material adding and discharging heat exchanger is connected to hydrogenation feed heater. The bottom of alkane water washing tower and olefin washing tower is connected to solvent recovery column. The top of the solvent recovery column is connected to isobutane finished column, reboiler and solvent recovery tower condenser. The solvent recovery column condenser outlet line is divided into two: where one pipeline is connected to upper part of the solvent recovery column, and the other pipeline is connected to the upper part of extractive distillation column. The bottom of the hydrogenation reactor is connected to hydrogenation material adding and discharging heat exchanger and hydrogenation separation means. The hydrogenation separation means is sequentially connected to the compressor suction tank, where the compressor and alkane water tower is connected to hydrogenation material adding and discharging heat exchanger via pipeline. The bottom of the hydrogenation separation device is connected to dehydration tower; and the bottom dehydration tower is connected to isobutane finished tower. An INDEPENDENT CLAIM is also included for preparing isobutane using the isobutane preparation system, comprising carrying out extractive distillation of etherified C4 to obtain butene products; carrying out extractive distillation of unsaturated C4 raw materials, then performing hydrogenation and separation to obtain isobutane product; and carrying out hydrogenation of saturated C4 raw material to obtain isobutane product.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the isobutane preparation system.