The characteristics of CO2 hydrate formation are investigated in three different systems including pure water, tetrahydrofuran (THF) and tetrabutyl ammonium bromide (TBAB). Results show that THF can improve the phase equilibrium conditions of CO2 hydrate at higher temperature 6-15℃. The effect of THF and THF/SDS on CO2 separation from CO2/N2 gas mixture have been studied under the conditions of 4.5-6MPa,0.5-6℃. Results show that the induction time is further shortened as well as the pressure drop is increased remarkably by adding 0.3 wt % SDS in 9 wt % THF system.CO2 recovery is increased by 10% compared with the single THF system. CO2 occupy the hydrate crystal caves rapidly by adding SDS which can improve the competitiveness of CO2 to N2.