The large hydrogenerator is the powerful heart of a hydropower station, serving as the core equipment for hydropower energy conversion, ensuring the stability of the national power system and enhancing the quality of electrical power. The stable and safe operation of a hydrogenerator depends greatly on the performance of core components such as the runner, rotor and thrust bearings which usually work under harsh conditions, including water erosion, environmental corrosion, bio-corrosion, strong magnetic and electrical fields, high speed and high stress. Thus, serious damages can be easily caused on the surfaces of these components. Surface engineering techniques, which can obviously improve the surface properties of the material, have provided an effective approach for strengthening the surface and extending the life of key components of hydrogenerator units.