The ground reaction force for a biped skating robot was calculated and analyzed, and a modeling method for the ground reaction force by using convex optimization was proposed. On the basis of reasonable assumption, the modeling of ground reaction force was transformed as a minimization problem of robot kinetic energy after collision under condition with certain constrains, and as a standard convex optimization form. By using CVX software of convex optimization to calculate and simulate the ground reaction force, the results prove the effectiveness of the method.