Abstract: Aiming at the problems of complex composition of blocking removal fluids for oil and water injection wells, poor targeting of conventional corrosion inhibitors, unclear corrosion inhibition mechanism, and difficulty in meeting on-site requirements for corrosion rate, a new Mannich base corrosion inhibitor PA-CM was synthesized using acetophenone, formaldehyde, and benzylamine as raw materials. The corrosion inhibition performance of PA-CM in four types of blocking removal fluids (hydrochloric acid system, fluoroboric acid system, polyhydric acid system, and depolymerization system) was investigated through corrosion rate calculated by weight loss method. The surface morphology and corrosion product composition of steel sheets before and after corrosion were analyzed by microscopic characterization techniques such as scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Combined with electrochemical tests and molecular dynamics simulation, the corrosion inhibition mechanism of PA-CM in different blocking removal fluids was explored. The results show that PA-CM exhibited good corrosion inhibition performance in all four blocking removal fluids. At 90 ℃, the corrosion rate of N80 steel sheet in the hydrochloric acid system containing 1% PA-CM was only 1.07 g/(m²·h), which was much lower than that in the industry standard requirement. The order of corrosion rate of N80 steel sheet in the four blocking removal fluids was: hydrochloric acid system, polyhydric acid system, depolymerization system, fluoroboric acid system. After adding 1% (mass fraction) PA-CM, there were no obvious corrosion traces on the steel sheet surface, and the surface roughness was significantly reduced. C-N bonds and C=O (carbonyl groups) were detected on the surface of steel sheets corroded by the four blocking removal fluids, confirming the formation of corrosion inhibitor adsorption films. The adsorption energy of PA-CM was much higher than that of various corrosive particles in the blocking removal fluids, and it could preferentially adsorb on the steel sheet surface to form a dense protective film. Moreover, it had a strong inhibitory effect on the diffusion of corrosive particles, which could effectively isolate the contact between the corrosive medium and the steel sheet surface, thereby significantly inhibiting steel sheet corrosion. This study can provide a theoretical basis and technical support for the selection and on-site application of corrosion inhibitors for blocking removal in oil and water injection wells.