Abstract: ABSTRACT:The erosion problem of flow-parts in hydroelectric equipment has always been a major challenge for the hydroelectric industry. Understanding the erosion mechanism is crucial to solving this problem. This article provides a comprehensive overview of the erosion mechanism of flow-parts in hydroelectric equipment from multiple perspectives, including cavitation erosion, sand abrasion, and the combined effect of cavitation erosion and sand abrasion. These overviews provide a theoretical basis for the design of flow-parts in hydroelectric equipment and the selection of surface protection technologies. In addition, this article also reviews the main protective technologies for flow-parts in hydroelectric equipment, summarizes their research progress, existing issues, and future development trends. These protective technologies include coating technology, surface modification technology, welding repair technology, etc. Understanding the advantages, disadvantages, and limitations of these technologies can provide guidance for the hydroelectric industry in selecting appropriate protective technologies. Through the research in this article, the aim is to provide guidance for the study and application of erosion problems, in order to promote the sustainable development of the hydroelectric industry. Resolving the erosion problem will help improve the service life of hydroelectric equipment, reduce maintenance costs, enhance the stability and reliability of hydroelectric power generation, and further promote the development and progress of the hydroelectric industry.