In order to meet the harsh mining conditions of high temperature and high salinity in Northwest China oilfield，a quinoline quaternary ammonium salt corrosion inhibitor QA was synthesized. The structure of the synthesized samples were analyzed by infrared spectroscopy，the corrosion inhibition effect of the corrosion inhibitor QA under high temperature and high Cl- concentration condition was evaluated by high temperature and high pressure dynamic reactor experiment. In addition，the corrosion inhibition mechanism of QA was probed by the molecular dynamics simulations experiments. The results showed that the inhibition efficiency of quinoline quaternary ammonium salt QA on N80 and P110 steels was above 92% at 140°C and Cl- concentration of 30， 000 mg/L，exhibiting good corrosion inhibition effect. In addition，molecular dynamics simulations showed that the corrosion inhibitor could replace the Cl- on the metal surface，reduce the contact between the metal and Cl-，and delay the corrosion reaction of Cl- on the metal surface. At the same time，the presence of the corrosion inhibitor QA could reduce the adsorption energy of Clon the metal surface，so it could delay the Cl- corrosion effect on metal corrosion，as a result，the QA played a higher inhibition effect.