Optimization method for Coulomb potential by Natoli was improved,in which simple polynomial basis functions are used to fit slowly varying long-rang part of potential,and limited conditions are set to enhance consistency.Without increasing computational complexities,an optimal potential with lower mean squared difference is obtained.Cutoff criterion in real and reciprocal space determining optimal breakup of exact potential is suggested k_cr_c ≥ 15.New potential was tested on dense liquid hydrogen which shows lower pressure and energy than Natoli and Ewald potentials.