The separation of carbon dioxide (CO

2

) is of great importance for environment protection and gas resource purification. The ionic liquids (ILs)-based gas separation membrane provides a new chance for efficient CO

2

separation

while high permeability and selectivity of membranes is a great challenge. In this study

the influence of two protic ILs with different anion ([TMGH

]

[Im

]

and [TMGH

]

[PhO

]

) on the CO

2

separation performance of the prepared ILs/Pebax blended membranes were systematically investigated at different temperature. The results showed the CO

2

permeability exhibits the rising trend for ILs/Pebax blended membranes with the increment of IL content. Especially

the [TMGH

]

[Im

]

with low viscosity and high CO

2

absorption capacity leads to the blended membranes showing better CO

2

permeability and ideal CO

2

selectivity than that of membranes with [TMGH

]

[PhO

]

at high IL content. Besides

with operating temperature increasing

the gas permeability of 20% (mass) [TMGH

]

[Im

]

/Pebax blended membrane increases due to the decreasing viscosity of IL and the rising chain mobility of polymer. Inversely

the gas selectivity shows decreasing trend because CO

2

absorption capacity obviously decreased at higher temperature.