Deep excavation accidents occur frequently

which result in rather huge economic losses and bring negative effects to the society.In this paper

the reasons of excavation accidents are summarized firstly.Then an effective reliability analysis method called Fault Tree Analysis（FTA） is introduced and applied to the safety assessment of deep excavation engineering with examples of piles-in-row supporting system and slope supporting system.The fault trees of the piles-in-row supporting system and the slope supporting system are built

and qualitative analyses are done for them.At last

a quantitative analysis is applied to a foundation excavating project using slope supporting system

which illuminates the usage of FTA on the safety assessment of deep excavation engineering.