Abstract: The subgrade reacting force in different stages through construction pericd is measured by in-site testing of a real sluice with tenons under the foundation mat, the corresponding subgrade reacting force is worked out by FEM(finite dement method). By comparing and analysing of the observed value and computational results, it is found that the subgrade reacting force is nonuniform and concentrated under the tenons. With the increasing of the lead from upper, subgrade reacting force inclines to be uniform.