The corrosion resistance of commercially pure (CP) titanium in 1% NaCl+0∼1% NaF solution (pH=6) under different elastic tensile strains was investigated by using electrochemical impedance spectroscopy (EIS) measurement technique. The polarization resistance ( R p), which is inversely proportional to the corrosion rate, of CP titanium in the test solution was obtained from the EIS data. Different elastic tensile strains, namely 0%, 1%, 2%, and 4%, were applied on the test specimens by using a tensile test machine during the corrosion tests. Corrosion morphology was characterized by using a scanning electron microscope. Surface chemical analyses were performed by using energy dispersive spectroscopy and X-ray photoelectron spectroscopy. The results showed that the NaF concentration and the elastic tensile strain had a statistically significant influence on the R p ( P<0.001). The R p decreased on increasing the NaF concentration and the elastic tensile strain. When the NaF concentration was lower than 0.01%, the R p value (>3.4×10 5 Ω cm 2) was mainly ascribed to the formation of a protective titanium dioxide (TiO 2) on the metal surface, regardless of the elastic tensile strain applied. However, when the NaF concentration was higher than 0.1%, the protectiveness of TiO 2 was destroyed by fluoride ions, leading to severe corrosion of CP titanium.