It is well known that study on stress and abutment stability of high arch dam under complex environment plays an important role in dam construction and operation successfully. High arch dam studied in the paper will be constructed in a complex geological site

where a large number of faults

altered rock

mantle rock existing in the dam foundation and abutment

which will yield asymmetrical displacement in both abutments

increasing compression deformation and bearing capacity limit of abutment so as to influence normal operation state and decrease stability of dam abutment. Then 3-D finile element analysis is applied to the arch dam and abutment under different operation modes

studying stress and displacement of dam and dam abutment corresponding to their distributing features

and analyzing possible failure pattern

process and mechanism. The results illuminate the arch dam is instable when unreinforced; so reasonable reinforcement measures are adopted in the arch dam including six actuating holes in the right dam abutment and anchor holes in the left dam abutment. And then 3-D finile element analysis is applied to the arch dam and abutment after reinforcement

of which results show that the reinforcement is effective for the arch dam stability

which improves stress and displacement distribution conditions in connection with stability of abutment rock; but the left dam abutment is still instable so as to add anchor holes area to ensure the arch dam stability.