In this study, two novel environmental benign double antibiotic norfloxacin or ciprofloxacin scaffolds included branched molecules were prepared by multi-step routes and purified by simple performance, which were used as the target compounds (TCs). Meanwhile, a single norfloxacin or ciprofloxacin skeleton based molecules were synthesized as the reference compounds (RCs). The molecular geometry optimization and material simulation computation revealed that TCs presented smaller HOMO-LUMO energy gaps and larger binding energy levels on mild steel surface than RCs. The chemical adsorption of TCs on steel surface was confirmed by X-ray photoelectron spectroscopy, which could be processed by TCs chelation with iron ions. It was shown that TCs could be self-adsorbed on steel surface, which was demonstrated by atomic force microscopy and scanning electron microscopy. The anticorrosion of the studied compounds for mild steel in HCl solution was investigated by electrochemistry analysis. The results suggested that the anticorrosion efficiency could reach 95.86% (TC1) and 97.05% (TC2) at 0.050 mmol·L⁻¹ based on electrochemical impedance spectroscopy, which were much better than RCs (RC1, 69.23%; RC2, 74.16%). The adsorption isotherms of TCs on steel were further fitted, and a deep insight on adsorption was discussed.