A series of novel phthalazinone-based copolymers with intrinsic microporosity (PHPIMs) was successfully prepared by an aromatic double nucleophilic polycondensation reaction of a designed and synthesized, new rigid and twisty monomer, tetrahydroxyl-phthalazinone (TPHPZ), with 5,5', 6,6'-tetrahydroxy-3,3,3', 3'-tetramethyl-1,10-spirobisindane (TTSBI) and 2,3,5,6-tetrafluoroterephthalonitrile (TFTPN). These copolymers showed excellent solubility in common organic solvents, and were employed to prepared membranes. The gas transportation properties of the resultant membranes were also investigated. The thermal analysis, GPC characterization and 77 K nitrogen adsorption results indicated that all the copolymers exhibited excellent thermal stability, high molecular weight, and high BET surface areas ranging from 693 to 812 m(2)/g. The gas separation performance of the polymer membranes demonstrated that the ideal selectivity (alpha) of H-2/N-2, O-2/N-2, CO2/N-2 and CO2/CH4 gas pairs of the obtained PHPIMs exhibited an effective improvement, surpassing the 2008 Robeson plot for the gas pair CO2/CH4 and approaching the 2008 Robeson upper bound for gas pairs of H-2/N-2 and O-2/N-2, while accompanying with the decrease of the permeability for the increase of the polymer chain stiffness and the physical aging behaviors.