This article has described a new design method for dipping tank structure under hydrostatic pressure，based on the example of large-scale dipping tank in automobile finishing production line.The tank models were estalished with traditional and new method respectively by use of Inventor finite element analysis technique.Through analysis，calculations and comparison，the stress and deformation in each part of the tank were indicated，while the weak part of the design was showed out and be optimized.The simulation results showed thatthe large-scale dipping tank structure designed with this new method was more reasonable andeconomic.