TECHNOLOGY FOCUS - POLYMERS - Preparation (claimed): Raw materials and salt-forming agent are added to a reactor provided with a water separator, solvent is added, and stirred for 2-5 hours. Distilled water is added to obtained mixture and reacted at 150-180 degrees C for 4-10 hours. The reaction product is poured into water, stirred at 0-30 degrees C and crushed. The obtained powder material is washed with distilled water to remove inorganic salt, further washed with ethanol to remove solvent and organic impurities, and dried, to obtain amino-containing crosslinked polyarylethersulfone. The salt-forming agent is anhydrous potassium carbonate. The solvent is toluene, water and sulfolane. The raw materials include 4,4-dichloro-diphenyl sulfone, 4-amino-phenyl-hydroquinone, 3,3-diallyl biphenyldiol and biphenyldiol. The molar ratio of 4-amino-phenyl-hydroquinone, 3,3-diallyl biphenyldiol and biphenyldiol is 0.1:0-0.2:0.9-0.7. The molar ratio of total content of 4-amino-phenyl-hydroquinone, 3,3-diallyl biphenyldiol and biphenyldiol, 4,4-dichloro-diphenyl sulfone and salt-forming agent is 1:1-1.04:1-1.5. Preferred Process: The amino-containing crosslinked polyarylethersulfone film is prepared by mixing amino-containing crosslinked polyarylethersulfone and N-methylpyrrolidone in the mass ratio of 1:10-20 g/mL, casting obtained mixed solution into a film, and drying. The amino-containing crosslinked polyarylethersulfone thermally-crosslinked film is prepared by mixing amino-containing crosslinked polyarylethersulfone and N-methylpyrrolidone in the mass ratio of 1:10-20 g/mL, adding benzoyl peroxide, casting obtained mixed solution into a film, and drying at 150-200 degrees C for 1.5-2 hours under inert gas atmosphere. The amino-containing crosslinked polyarylethersulfone/carbon nanotube gas separation membrane is prepared by mixing carboxylic acid-modified carbon nanotubes and N-methylpyrrolidone in mass ratio of 1:200-700 g/mL, ultrasonically dispersing for 4-8 hours, obtaining solution (A), mixing amino-containing crosslinked polyarylethersulfone and N-methylpyrrolidone in the mass ratio of 1:10-20 g/mL, mixing obtained solution with solution (A), casting mixed solution into a film, and drying. The amino-containing crosslinked polyarylethersulfone/carbon nanotube thermally-crosslinked gas separation membrane is prepared by mixing carboxylic acid-modified carbon nanotubes and N-methylpyrrolidone in mass ratio of 1:200-700 g/mL, ultrasonically dispersing for 4-8 hours, obtaining solution (A), mixing amino-containing crosslinked polyarylethersulfone and N-methylpyrrolidone in the mass ratio of 1:10-20 g/mL, mixing obtained solution with solution (A), adding benzoyl peroxide, stirring, casting obtained mixed solution into a film, and drying at 150-200 degrees C for 1.5-2 hours under inert gas atmosphere. Preferred Composition: The mass ratio of carboxylic acid-modified carbon nanotubes and amino-containing crosslinked polyarylethersulfone is 1-3:97-99. The amino-containing crosslinked polyarylethersulfone gas separation membrane contains composite material containing 1-3 %mass carbon nanotubes and remainder of amino-containing crosslinked polyarylethersulfone. The mass ratio of total content of carboxylic acid-modified carbon nanotubes and amino-containing crosslinked polyarylethersulfone, and benzoyl peroxide is 1-3:97-99. The amino-containing crosslinked polyarylethersulfone thermally-crosslinked gas separation membrane contains composite material containing 1-3 %mass carbon nanotubes, and remainder of amino-containing crosslinked polyarylethersulfone and benzoyl peroxide. The mass ratio of amino-containing crosslinked polyarylethersulfone and benzoyl peroxide is 19-99:1.