This invention presents a process of butadiene-1,3 extraction. The process consists of the procedure of 1st extractive fractionation, 2nd extractive fractionation, distillation and alkyne fractionation. This invention can improve the yield and capacity of butadiene extraction unit by adding an alkyne fractionator to the existing butadiene extraction unit and appropriately adjusting the process condition of 1st and 2nd extractive fractionators. This invention can decrease the energy and material consumption per unit of butadiene-1,3, which greatly improved the economic profit. The investment on various scales of butadiene extraction units for adding alkyne fractionator is almost same. Further more, the profit is in direct proportion with the scale of a plant and output is in several to some dozens of folds to investment. After the implementation of this invention, the discharge of vinyl acetylene offgas can be reduced by around 3400 tons per year, which mitigate the pollution on environment and save energy. The effect of energy saving and emission reduction is remarkable.