In order to meet the requirements of high temperature acidizing, a new acid gelatinizer was synthesized by chosing non ionic monomer AM, complex cationic monomer H-DMDAAC, anionic monomer AMPS as starting materials and redox system as initiator in aqueous solution at low temperature. Various factors influencing polymerization reaction were analyzed, the optimum conditions of polymerization were determined, the basic performance of gelling acid was evaluated and its action mechanism was studied. The results show that it has good property to increase viscosity, resistance to high temperature and acid-rock reaction retardation, the viscosity of acidizing fluid of 20% mass fraction can reach 37.5 mPa·s at 150 ℃ and shearing rate of 170 s ^-1 when the mass fraction of YJN-1 is 1%. Mass fraction of gelling acid remains 11.9% after 60 min's reaction with limestone at 90 ℃, which is 7 times more than that of common acid, it can meet the need of acidizing in high temperature wells.