It is often noted that there exist a number of residue water-stains on the alloy surface after removing carbon deposits on TC4 Ti-alloy surface by alkaline-washing and subsequent high-temperature water-washing, which can seriously interfere the subsequent fluorescence analysis. Herein, the electrochemical corrosion behavior of TC4 alloy in 10% (mass fraction) NaOH solution at various temperatures is assessed via electrochemical workstation, optical microscopy and SEM+EDS, aiming in understanding the formation mechanism of the residue water stains during the removal process of carbon deposits. The results show that with the increasing alkaline solution temperature, the corrosion rate of TC4 alloy accelerates.Results of OM and SEM+EDS characterization show that the emerge of residue water-stains may be closely originated from spots where the existing passivation film was corroded by the concentrated residue alkaline solutions on the alloy surface. Furthermore, after being cleaned with alkali solution of the test parts of the alloy, then they are comparatively cleaned with deionized water and tap water respectively. It shows that with the increase of water temperature, the residue water-stains can be clearly observed on the surface of the test parts. Fortunately, the utilization of deionized water instead of tap water can effectively avoid the occurrence of the residue water-stains.