Objective To study the effect of imidazoline corrosion inhibitor on the stress corrosion cracking (SCC) behavior of P110 steel in simulated annulus environment in CO2 injection wells, in order to provide reference and basis for the establishment of protection method against corrosion in the annulus environment of CO2 injection wells. Methods P110 steel in simulated annulus environment in CO2 injection wells was treated by SCC tests, electrochemical measurements and corrosion morphology analysis. According to the site-extracted component analysis results of annulus medium in the CO2 injection well, simulated solution was prepared in laboratory, imidazoline corrosion inhibitor was selected, and the pH of the simulated solution was adjusted to 4. Highly pure N2 was introduced to deoxidize, in order to prevent the oxidation of sulfide. Three-point bend specimen was used in the stress corrosion test, and the deflection of the sample was controlled at the set value to control the load. Both the stress corrosion test and electrochemical test were carried out in a closed autoclave. After the experiment, the corrosion morphology was observed by scanning electron microscope. Results In the annulus environment of the CO2 injection well, concentration of imidazoline corrosion inhibitor had important effect on the SCC behavior of P110 steel. In the presence of tensile stress load, the addition of sufficient corrosion inhibitor had good inhibition effect on uniform corrosion and SCC, but when the dosage was insufficient, the addition of corrosion inhibitor would increase the SCC sensitivity of P110 steel, and the SCC mechanism was the mixed mechanism of local anodic dissolution and hydrogen embrittlement. Therefore,SCC occured on P110 steel in simulated annulus environment in CO2 injection wells, and its mechanism was AD+HE. Conclusion The concentration of imidazoline corrosion inhibitor posed a significant influence on the SCC behavior of P110 steel. Adequate imidazoline corrosion inhibitor could well inhibit both uniform corrosion and SCC, while the addition of inadequate imidazoline corrosion inhibitor increased the SCC susceptibility instead.