Abstract: SBS block resin has a unique structure in which soft and hard segments are combined with each other, and gas molecules can be separated by extrusion. In this study, a series of x-SBS/Tetrahydrofuran (THF) resin solutions were used to prepare the corresponding SMS-x separation membranes with porous α-Al₂O₃ ceramics tubes as the carrier. FT-IR, XRD, SEM and other characterization test results show that the SBS resin can be well combined with the carrier, and the thickness of the separation membrane is less than 50 μm. The gas test shows that the SMS-20 separation membrane has the best CH₄/N₂ gas selectivity in the pressure range of 0.05-0.3 MPa. At 0.1 MPa, α(CH₄/N₂) =3.81, and the molar flux of CH₄ is 1.41×10⁻⁶ mol·m⁻²·s⁻¹·Pa⁻¹. At 0.3 MPa, the CH₄ molar flux of SMS-10 is the largest, which can reach 3.47×10⁻⁶ mol·m⁻²·s⁻¹·Pa⁻¹. In addition, the test of different proportions of mixed gas verifies that the separation membrane prepared in this paper can also be competent for the corresponding separation work. All the separation membranes prepared in this paper can stably separate gas for up to 7 days at a pressure difference of 0.1 MPa, and have good performance stability. Therefore, the porous α-Al₂O₃ substrate SBS separation membrane can have both excellent permeation flux and gas selectivity, and provide a favorable choice for the enrichment of coalbed methane CH₄.