Abstract: As a style of anchoring the cable of suspension bridge,the gravity anchor is one of the most important elements for the safe of the bridge.The displacement of the anchorage buttress is the key factor for the stability.This paper examines the stability of the anchorage for a Super Cable-stayed Bridge planned to be built over Longjiang river in Yunnan Province.It is located in the place with complex stratum condition.The soil strength and modulus parameters are very small at the construction site.Therefore,predicting the displacement of anchorage buttresses under various conditions is very important to design the proposal of foundation treatment and determine treatment parameters reasonably.This paper presents the large-scale numerical models with FLAC3D-fast lagranian analysis of continua in three-dimensions.The models are developed in strict accordance with the construction steps.They include foundation pit excavation,main body of anchorage construction,backfill and weights construction,and cable connection.The results indicate that the displacement of the anchorage buttress in the last two steps is about 5cm,lower than the allowable value 15cm.The settlement of foundation pit is in the allowable limits,too.The soil needn't to be strengthened.Because the displacement is largely dependent on the soil parameters,we also conduct the parameters sensitivity analysis.Results indicate that the deformation modulus E is ought to be assured through enough tests for its big sensitivity value.