The invention relates to a method for spearing butane from butylene with the multicomponent compound of ionic liquid, saline, ethyl methyl ketone and N-formylmorpholine. The content of ionic liquid in the multicomponent compound is 1.0 to 95 percent; the content of the saline in the multicomponent compound is 0.5 to 20 percent; the electropositive ion of the ionic liquid is iminazole electropositive ion, alkyl imidazole electropositive ion or alkyl quaternary ammonium ion, or the compound thereof; the electronegative ion is tetrafluoroborate electronegative ion, hexafluorophosphoric acid electronegative ion, nitrate ion, tetrachloro aluminic acid iron, heptachlor bi aluminic acid iron, chloride ion, bromine electronegative ion or the mixture; and the ionic liquid can be dimethylformamide potassium thiocyanate compound salt, dimethylformamide sodium sulfocyanate compound salt, or the compound; the saline is potassium thiocyanate, sodium sulfocyanate, ammonium thiocyanate, sodium nitrate, potassium nitrate, sodium iodide, potassium iodide, zinc chloride, copper chloride, zinc chloride, potassium bromide, or the compound thereof.