The work aims to study health toxicity and ecotoxicity of quinoline, 5-benzylquinoline and 8-hydroxy- 5-benzylquinoline, and their corrosion inhibition performance on mild steel in 1 mol/L HCl. The T.E.S.T software was utilized to estimate toxicity of the three quinoline derivatives and select environment-friendly inhibitors. Meanwhile, potentiodynamic polarization curve was used to investigate and further compare inhibition behavior of these inhibitors. In addition, corrosion inhibition mechanism was preliminarily explained based upon adsorption isothermal model. Toxicity calculations showed that 5-benzylquinoline had no mutagenicity (Ames test) and developmental toxicity, oral rat LD50 was at level 5. 8-hydroxy-5-benzylquinoline; 8-hydroxy-5-benzylquinoline had mutagenicity but no developmental toxicity; and quinoline had both mutagenicity and developmental toxicity. According to potentiodynamic polarization curve, 5-benzylquinoline and 8-hydroxy-5- benzylquinoline exhibited excellent inhibition performance on mild steel in 1 mol/L HCl (ηp(5-benzylquinoline)= 94.74% and ηp(8-hydroxy-5-benzylquinoline)=98.06% at 1 mmol/L concentration). However, the inhibition performance of quinoline was nearly saturated at 1 mmol/L concentration since inhibition efficiency was nearly 85%. According to movement of self-corrosion potential, three inhibitors were all mixed-type inhibitors. Furthermore, adsorption of these inhibitors on mild steel could be fitted ideally by Langmuir adsorption model, which belonged to mixed physical chemical adsorption. 5-benzylquinoline is an environment-friendly inhibitor. Inhibition performance of 5-benzylquinoline and 8-hydroxy-5-benzylquinoline be obviously superior to that of quinoline, which can be explained that benzyl and hydroxy groups enhance stability of inhibitor molecule chemical adsorption on metal surface, a dense protective film takes shape and effectively reduces corrosion of mild steel.