[en] Fuel assembly bowing may induce the reloading or unloading difficulties, and the incomplete insertion of control rod. The fretting between fuel assemblies could result in the component damage and the leakage of nuclear fuels. These phenomena directly affect the safe operation and economic benefits of nuclear power plants. This paper summarizes the typical mechanic problems, such as bowing, fretting, and integrality analysis in PWR fuel assembly research and development. The key factors, resolving methods and prospect are also proposed. (authors)