Vie report a finding that not only the micelles but also the premicellar aggregates of a star-like tetrameric quaternary ammonium surfactant PATC can disassemble and clear mature beta-amyloid A beta(1-40) fibrils in aqueous solution. Different from other surfactants, PATC self assembles into network-like aggregates below its critical micelle concentration (CMC). The strong self-assembly ability of PATC even below its CMC enable PATC to disaggregate the A beta(1-40) fibrils far below the Charge neutralization point of the A beta( 1-40) with PATC. There maybe two key features of the fibril disassembly induced by the surfactant First, the positively charged surfactant molecules bind with the negatively charged A beta(1-40) fibrils through electrostatic interaction. Second, the self assembly of the surfactant molecules bound onto the A beta(1-40) fibrils disaggregate the fibrils, and the surfactant molecules form mixed aggregates with the A beta(1-40) molecules. The result reveals a structural approach of constructing efficient disassembly agents to mature beta-amyloid fibrils.