The ground state energies of helium - like atoms are studied by using the Hamiltonian substitution method. 　　The calculated results are the same as those from the one - parameter variational approach and agreement in well 　　with experiment than the values from the first - order perturbation method. The present calculation is simple and comparatively 　　accurate，without the need for trial wave function and the limitation by the perturbation magnitude，so that the 　　Hamiltonian substitution method is an excellent choice for teaching.