Gas separation performance of glassy polymers can be improved by enhancing the polymer backbone stiffness to decrease the chain packing and increase the free volume and gas permeabilities. In this work, two Troger's base (TB)-based polymers were prepared by polymerization from two spirobichroman-containing diamine monomers, MSBC and SBC. The obtained TB-based polymers show good solubility in polar aprotic solvents including DMF, DMAc, NMP, and DMSO, high molecular weight, and high thermal stability. Gas separation performance of TB-MSBC and TB-SBC are much better than those of the 6FDA-MSBC and 6FDA-SBC, especially for H-2/N-2 and H-2/CH4 gas pairs. Furthermore, the CO2 permeability of TB-MSBC is about 7.6 times higher than that of 6FDA-MSBC. The much-improved separation performance of TB-based polymers can be mainly attributed to the ineffective chain packing via the incorporation of the spriobichroman structure and a ladder-type bridged bicyclic TB unit.