Iso-butane, n-butane and butylene separation and purification method

The invention provides an iso-butane, n-butane and butylene separation and purification method. C4 raw materials are successively put into a C3 decarburization tower, a C5 decarburization tower, an iso-butane tower, an n-butane tower and a stripping tower to obtain high-purity iso-butane, n-butane and butylene. Solvents are cyclically utilized. The iso-butane, n-butane and butylene separation and purification method has the technical advantages that not only can equipment investment be reduced, but also the advantages of extractive distillation are used and the energy consumption is reduced.