Abstract: Inspection,analysis and reliability theories and methods for Gandjelas gravity dam are introduced in this paper.It is indicated that construction joints are the main cracks in the concrete gravity dam,with the depth of the main cracks being about 600 mm,and the depth of minor cracks being 200 mm.The integrity of the dam is deceased by cracks of upstream face and corridor,and leakage inevitably occurred after water level rising.Integral stability and reliability of the gravity dam is slightly deficient,and the stress distributions of the dam body correspond with "DL5108-1999 Design Specification for Concrete Gravity Dams".Considering structural safety,function and durability,horizontal construction joints are reqarded as dangerous cracks,which need to be repaired.Pre-stress anchor system and anti-permeation system are proposed to solve the delaminating of construction joints and dam leakage.NBS mortar is introduced on the spillway for repair and maintenance,and grouting permeability reducing admixture is used to repair the horizontal construction joints and cracks on the wall of the corridor.