The foundation pit supporting design in deep soft soil sites is often affected by unbalanced soil pressure, so it is necessary to take appropriate supporting measures to ensure the safety of construction. Based on the deep foundation pit project of a riverfront section in the Nansha District of Guangzhou, this paper studies the optimization of deep foundation pit support design under the condition of unbalanced soil pressure in a deep soft soil site. The project is located in an area of deep soft soil, with one side facing the road and the other facing the river. Through the comprehensive analysis of the site engineering and hydrogeology and other aspects, carried out the deep foundation pit supporting structure optimization research, and compared with the three-dimensional numerical simulation results and field monitoring data. Finally, a supporting structure system combining long and short piles with supports or large-diameter anchor cables is selected to coordinate the deformation caused by the unbalance of earth pressure on the riverfront side of the foundation pit. The comparison and analysis of the monitoring data and calculation results show that the selection of the support scheme is reasonable, can meet the safety requirements of the foundation pit and surrounding environment, and has economic performance.