Abstract: To improve anti-radiation performance, a soft-error optimal placement method for combinational circuits based on charge sharing is proposed. The algorithm enhanced the pulse quenching effect by reducing the distance between the existing quenching pairs. By inserting and reordering placement methods, the number of quenching pairs was increased, and the occurrence probability of pulse quenching effect was improved. A soft-error optimization placement and evaluation platform for combinational circuit was implemented. It could be used independently, or be embedded into commercial tools. The simulation results show that the method can reduce the pulse width that is eventually captured, and reduce soft errors by 14% ~26%.