Abstract: The Solvents for extractive distillation to separate ethane/ethylene are studied and screened.Infinite relative volatility and infinite selectivity of 11 solvents with dipole moment from 0 to 11.36 are determined by gas stripping,which draws the conclusion that the selectivity of the solvent increases with its polarity.Two solvents, ACN and DMF, which have higher selectivity,are modified by adding water and salt, respectively.It is found that the effect of separation improves after modification, but the improvement is limited.