The aim of this work was to study the degradation behavior of Ti-6Al-4V alloys for dental applications in acidic artificial saliva with fluoride ion using electrochemical techniques, optical microscopy, scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS). The experimental results showed that fluoride ion had significant influence on the degradation of Ti-6Al-4V alloys, and there was an obvious critical concentration of fluoride ion (about 0.1wt%). With increasing fluoride ion concentration, the corrosion potential (E-corr) of alloys moved toward negative and the impedance of alloys decreased, meanwhile, noticeable transformation from minimum corrosion to severe pitting corrosion was observed on alloys surface following the dissolution of TiO2 passive films, leading to the decrease of the corrosion resistance of alloys. The electrochemical dissolution of TiO2 passive films involved a nucleophilic attack of fluoride atom to the titanium atom of TiO2. In addition, Ca2+ and Na+ in acidic saliva may involve the surface reactions and make the reactions more complex.