Abstract: Taking the open caisson foundation in Sutong Bridge as the engineering background, the influence of the location of the vertical artificial boundary set in soil layer on the seismic response analysis of the foundation has been analyzed by numerical analysis. The variation tendency of the seismic responses of the soil layer and the foundation with different soil region considered in calculation is studied. The result can be used as reference for the analysis of the large-scale open caisson foundation by the finite element method. When the model is in L/H=4 with the vertical artificial boundary, the effect of vertical artificial boundary in soil layer on the seismic responses of the open caisson, such as the moment, shear and axial force of the elements, can be controlled below 1% of relative errors.