In this study, CO2 capture from (67.00 mol %) CH4/CO2 mixed gas with tetra-n-butylammonium bromide (TBAB) solution at 281.3 K through a pressure recovery of hydrate separation method were studied. During the experiment, pressure was recovered by TBAB solution injected into the cell to improve the separation efficiencies of CO2 and the effects of the concentration of TBAB solution and the operating conditions was investigated. The results showed that the CH4 concentration in the gas phase could achieve 93.52 mol % with a pressure recovery method at 1.14 MPa and 0.293 mol % TBAB. Under the pressure of 1.14 MPa and 0.1 mol % TBAB, the maximum CO2 separation factor was 52.87 and the CH4 separation and recovery factor was 2.050. The results demonstrated that the pressure recovery method can significant enhance the separation efficiency of hydrate separation. It is an effective method to cut down energy consumption of hydrate-based gas separation.