Abstract: Effect of polyampholyte structure on the interactions between negatively charged poly(2-(dimethylamino)ethyl methacrylate)-b-poly(acrylic acid) (PDMAm-b-PAAn) and cationic gemini surfactant hexylene1,6-bis(dodecyldimethylammonium) dibromide (C12H25(CH3)2N(CH2)6N(CH3)2C12H25·2Br-) (abbreviation for 12-6-12) was studied by zeta potential measurement, fluorescence spectroscopy, surface tension and viscosity measurement. It was shown that micellelike aggregates or complexes could form between PDMAm-b-PAAn and 12-6-12 due to the electrostatic interaction and they were stabilized by the weakly hydrophilic PDMA segment. Diblock polyelectrolytes with different lengths of PDMA and PAA segment had the same conformation in the solution and the same interaction mode with gemini surfactant.