Abstract: Aiming at the phenomenon of ring crack and blade ablation of turbine nozzle of an aero-engine, the formation reason and repair of the defects were carried out from viewpoints of material, technology and application.The results show that the crack is of the ring formed by the generation and propagation of tearing crack caused by solder precipitation, and crack of the ring does not reappear after TIG repair.The blade ablation is formed by the dissolution of TGO by CMAS at the blade leading edge under high temperature.The blade ablation can be repaired by blade replacement, and the turbine nozzle achieves the requirements for the service life of assemblage utilization.