Abstract: Guanhui intercity rail foundation pit was a ultra-deep foundation pit constructed by the optimized support scheme. Based on the monitoring data,the authors studied the horizontal displacement of the pile,horizontal displacement of the pile top,ground settlement,strut axial force,groundwater fluctuation regularity during the process of excavation comprehensively and thoroughly. The results show that dewatering has a great impact on ground settlement which should be paid attention in construction;the steel support prestress has a great influence on foundation pit deformation,especially on the lateral displacement of the pile; steel support actual axial force is much smaller than the design value,the design scheme can be further optimized; and the optimized support scheme has limited the deformation of foundation pit very well.