Abstract: Through analysis of field test results drawn from pile-raft foundation settlement and reaction force of Shaanxi Postal Telecommunication Net Centre Building,a three-dimensional finite element model of ultra-high tube-in-tube structure,pile-raft foundation and subsoil is established by use of large-scale finite element software ANSYS,elastoplastic constitutive relation and medium plate theory;and non-linear numerical interaction analysis of the three under vertical loadis also done.Observed data of foundation settlement,proportion of pile to soilshare,etc.correspond well with those of numerical analysis.Further,pile-raft foundation settlement,force receiving and proportion of pile-soil share of ultra-high building in loess area are discussed.The analysis results indicate:adoption of super-lengthy perfusion pile has remarkable effect to decrease settlement in loess area,tube structures contribution to foundation rigidity ranges about 8 floors,which can reduce foundation differential settlement,the internal force distribution of the raft is very complicated,which is closely related with such factors as superstructure forms,piling arrangement and so on,moreover,the curving moment at rafts cantilever end is awfully great.