Taking the cross-sectional area of a gravity retaining wall as the objective function
and regarding the stability of gravity retaining wall and the bearing capacity of groundwork as restraint conditions
and then the problem of best cross-section selection of gravity retaining wall can be transformed to a question to solve a nonlinear optimal design under some specifical restrictions; and then to solve it by the PHR method. Base on the theory interpreted above
a corresponding program is compiled to solve the question; and the relationship between soil parameters and the optimum cross-sectional area is analyzed. At last
an example is given; it is shown that the optimum design is better than the original one.