Abstract: Several fractured steam turbine blades were discovered in the inspection process. The fracture causes of steam turbine blades were analyzed by macro analysis, metallographic examination, fracture micro analysis, and energy spectrum analysis and so on. The results show that steam and Cl^-, S^2-, Na⁺ reacted with steam turbine blades, produced local pitting corrosion on the blades, and formed corrosion fatigue source. At the same time, there were complex periodic alternating stresses such as centrifugal force and steam pressure on the blades, which eventually led to corrosion fatigue fracture of the turbine blades.