In order to explore the application effect of steel sheet pile support in the reconstruction project of urban renewal old road, using FLAC^3D numerical simulation as a research method, this paper analyzes the horizontal displacement, structural internal force and soil pressure changes of steel sheet piles in the actual excavation process, and draws the following main conclusions: 1) The horizontal displacement of steel sheet pile gradually decreases along the pile length direction. After the excavation of foundation pit, the peak value of the horizontal displacement of pile body appears at 1.5m near the secondary transverse brace, which increases by 9.21% compared with the peak displacement after the first excavation. 2) The peak moment of steel sheet pile appeared at the buried depth of 7.5m , and the peak shear force appeared at the buried depth of 8.3m . The internal force of steel sheet pile at the upper part of the first transverse brace was small, and the structural internal force reached the peak near the second transverse support. 3) The overall distribution trend of earth pressure after the pile increases with the increase of the buried depth. The distribution pattern of earth pressure after the secondary transverse bracing changes sharply from the peak value of 138.6kPa to 92.6kPa at the buried depth of 5.5m , with a decrease of 33.2% . After that, the earth pressure fluctuates until the end of excavation. The research results of this paper can provide some engineering guidance suggestions for the steel sheet pile foundation pit support engineering in urban road reconstruction projects.