NOVELTY - One-segment extraction, rectification and separation of carbon fraction is performed by feeding mixed carbon fraction in light components removing tower via rectification process; and extracting isoprene, cyclopentadiene, dicyclopentadiene and m-pentadiene from tower kettle; and feeding isoprene, cyclopentadiene, dicyclopentadiene and m-pentadiene in light components removing tower via rectification process; and extracting isoprene, pentane and amylene from the tower top.    USE - Method for one-segment extraction, rectification and separation of carbon fraction (claimed).    ADVANTAGE - The method improves extractant, improves selectivity of the extractant, cancels the 2-segment extraction and rectification unit, reduces the use amount and regeneration amount of solvent, and reduces operation cost.    DETAILED DESCRIPTION - One-segment extraction, rectification and separation of carbon fraction comprises:    (A) feeding mixed carbon fraction in light components removing tower via rectification process; the light components comprising carbon component, isopentane and alkyne; and extracting isoprene, cyclopentadiene, dicyclopentadiene and m-pentadiene from tower kettle;    (B) feeding isoprene, cyclopentadiene, dicyclopentadiene and m-pentadiene in light components removing tower via rectification process; extracting isoprene, pentane and amylene from the tower top; and sampling m-pentadiene, cyclopentadiene and dicyclopentadiene from the tower kettle;    (C) feeding materials comprising isoprene, pentane and amylene in middle of rectification tower; extracting solvent from upper part of the extraction and rectification tower; performing extraction and rectification in the presence of N-methyl pyrrolidone (NMP) by extracting the components comprising pentane and amylene from the tower top; and extracting solvent rich in isoprene from the tower kettle, the solvent containing NMP is a mixed solvent of NMP and salt solution; and    (D) feeding solvent material rich in isoprene in stripping tower for separation; extracting the solvent from the stripping tower top for extraction and rectification; feeding the materials containing isoprene obtained from the stripping tower top in isoprene rectification tower so that the isoprene is completely separated from the small amount of m-pentadiene, cyclopentadiene and dicyclopentadiene; and taking isoprene product from isoprene rectification tower top, in which the reaction and rectification process comprises generating dicyclopentadiene via dipolymer reaction of cyclopentadiene.