In view of the high temperature of carbonate reservoir in deep well and ultra deep well, it is difficult for conventional acid system to achieve the purpose of deep penetration. In this paper, based on acrylamide (AM) and self-made organic ammonium salt (ATCs), a high temperature resistant acid thickener with good performance was developed by optimizing monomer ratio, initiator content, initiator temperature, pH and chelating agent dosage. The results show that when m (AM): m (ATCs) is 5:8, initiator concentration is 300 mg / L, pH is 7, initiation temperature is 35 ℃, chelator dosage is 500 mg / L, the performance of the synthesized thickener is the best. Combined with Ostwald dewaele equation, the thickening ability of high temperature resistant thickener is evaluated. At 90 ℃, the consistency coefficient (602.85 mPa·sn) of the high-temperature resistant thickener is larger than that of the conventional thickener (544.57 mPa·sn), and the flow behavior index of the high-temperature resistant thickener is 0.51, which is smaller than that of the conventional thickener (0.54), showing better thickening performance. Compared with the conventional thickener, the high temperature resistant thickener has higher viscosity, lower viscosity drop rate and better temperature resistance at the same temperature. The viscosity of the high-temperature resistant thickener is 32.4 mPa·s, which is larger than the apparent viscosity of the conventional thickener (29.1 mPa·s) and shows better shear resistance when it is continuously sheared at 120 ℃ for 120 min at 170 s-1. Field application shows that the acid thickener has achieved good application effect in M block, Tarim Basin, and the single well production has increased from 8.3×10⁴ m³/d to 14.5×10⁴ m³/d.