Objective: To further reduce the cost of corrosion inhibitor, a low-cost cyclic imidazole corrosion inhibitor (S-S) was synthesized, and the corrosion inhibition properties and mechanism of S-S on N80 steel in 1.0 mol/L H2SO4 solution were studied. Methods: The corrosion inhibition properties of S-S on N80 steel in 1.0 mol/L H2SO4 solution and the corrosion inhibition mechanism were studied by weight loss experiment and electrochemical experiment. The rationality of the corrosion inhibition mechanism was further verified by surface morphology. Results: Under the weight loss experiment of 400.0 mg/L S-S in 1.0 mol/L H2SO4 at room temperature, the corrosion inhibition efficiency of EIS and Tafel were 95.79%, 98.05% and 95.76%, respectively. Electrochemical Impedance Spectroscopy (EIS) can prove that S-S can form a stable protective film on the surface of N80 and reduce the charge transfer rate, so as to exert excellent corrosion inhibition performance. The potentiodynamic polarization curve (Tafel) can indicate that S-S is a mixed corrosion inhibitor based on inhibitory anode, and S-S follows Langmuir isothermal adsorption equation in corrosion solution. DFT verifies the reactivity of S-S at the molecular level, mainly on S and N atoms; MD proves that S-S can be stably and spontaneously adsorbed on the surface of N80 steel; RDF proves that S-S forms a stable coordination with N80 surface. Conclusion: S-S can play an excellent corrosion inhibition performance in 1.0 mol/L H2SO4.