The invention provides a salting-out-rectification coupling-method dehydration method and device. The method comprises the following steps: S1, conveying a material to be treated into a rectification tower; under a heating condition, enabling azeotrope steam to sequentially pass through first-section filling, second-section filling and third-section filling; S2, after condensing the steam treated by the rectification tower, conveying the steam into a liquid-separation high-level tank and layering to obtain an upper-layer organic phase and a lower-layer saline water phase, which are separated from each other; S3, conveying the obtained organic phase into the rectification tower and circularly treating; concentrating an obtained water-phase layer through an evaporator and concentrating; conveying a concentrated solution into the liquid-separation high-level tank and cyclically utilizing; heating the rectification tower by utilizing water steam generated by concentrating. According to the salting-out-rectification coupling-method dehydration method and device, the rectification tower provided with the first-section filling, the second-section filling and the third-section filling is arranged, and separation of an acetonitrile-water azeotrope and a water phase in a tert-butyl alcohol-water azeotrope is realized; after the azeotrope is separated, an azeotropic point is broken to prepare anhydrous acetonitrile and anhydrous tert-butyl alcohol.