Abstract：Aimed at some limitation of the traditional BP Neural Network，a global optimal algorithm is put forward based on alternative and iterative algorithm，and the corresponding program of FORTRAN is developed. With the same initial condition，the Neural Network based on alternative and iterative algorithm is compared with that based on the traditional algorithm，and the characteristic and excellence of the former algorithm are explained. As an example，based on the nonlinear characteristic of ANN and 3D seepage flow FEM computation，the method combined with inversion principle is applied to the sluice foundation and the percolation parameter ratio is obtained. Compared with the actual value，the obtained result is accurate，which illuminates the reliability of the algorithm in back analysis.
