In order to improve the acidizing effect of acid in heterogeneous reservoir, an acidizing self-diverting agent was synthesized. An acidizing self-diverting agent ADDA with low viscosity and automatic thickening with acid rock reaction was obtained by free radical aqueous solution polymerization of four kinds of monomers, AM, DMAPMA, DMAAC-18 and ACMO. The best synthetic conditions were as follows: the molar mass ratio of AM:DMAAC-18:DMAPMA:ACMO was 90:1.8:10:10, the amount of initiator (V50) was 0.5% of the total monomer mass, the monomer concentration was 30%, the reaction temperature was 55 ?C, the reaction time was 6 h, the system pH was 7. The structure of the product was characterized by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (1H-NMR). The results showed that the molecular structure of ADDA was consistent with the design structure. At 90 ℃, the apparent viscosity of 1.3% ADDA acid solution can increase from 6 mPa?s to 126 mPa?s, which has good diverting performance. The apparent viscosity of 1.3% ADDA spent acid is 70 mPa?s after shearing at 90 ℃ for 1h at 170s-1, indicating that ADDA spent acid has good temperature resistance. The compatibility results showed that at 90 ℃, the apparent viscosity of 1.3% ADDA diverting acid of spent acid with acidification admixture was increased by 54 mPa?s compared with 1.3% ADDA diverting acid without acidification admixture, indicating good compatibility.