Abstract: This paper presents the key points for the maintenance of large turbines,and suggests that in the maintenance process,the clearance of components,alignment of shaft,bearings and sliding pin of the turbines shall be considered,and at the same time related data shall be carefully studied,and the analysis and evaluation shall be based on all the related factors.In this way,rational solutions may be proposed to ensure the effective maintenance and the safe and effective operation of the turbine unit.