The mesogenic monomer M and a series of main-chain liquid crystalline ionomers (LCIs) containing sulfonate groups were synthesized. The LCIs were prepared by an interfacial condensation reaction of mesogenic monomer 1,4-phenylene-dicarbonic acid bis (4-carboxyl phenyl) ester, brittle yellow (BY), 1,10-sebacoyl dihydroxy, and 1,12-dodecanedioyl dihydroxy. The sulfonate groups introduced to the main-chain backbone were confirmed by ultraviolet spectroscopy. The mesomorphic properties were investigated by differential scanning calorimetry (DSC), thermo gravimetric (TG), and polarizing optical microscopy (POM). Experimental results demonstrated that the glass-transition temperatures increased slightly, melting temperature decreased, and the mesophase temperature ranges increased first and then decreased with increasing content of sulfonate group. All of the polymers were thermally stable up to 320 A degrees C. The LCI (n) s exhibited typical nematic schlieren textures.