Abstract: The three fail form of scoring,fillister and corrosion for 127 mm (5″) S135 drill rod joint,corrosion rate and corrosion production have been researched by means of analysis of chemical composition and microstructure,testing of mechanical property. The results show that the material property of the drill rod joint are according to API standard,the corrosion mechanism is oxygen corrosion,corrosion production are mainly Fe3O4 and FeOOH and the scoring and fillister are formed because of incorrect application and seized flute.