Abstract: A circulating water electrochemical water softening system was established to study the effect of operating parameters on descaling. Experimental factors and levels including electrolysis voltage, spacing between electrode plates and initial hardness of the solution were determined. Orthogonal experiments were designed to analyze the influence of each factor on descaling quantity. The results show that the factors affecting removal efficiency are decreased in an order of initial hardness of the solution, electrolysis voltage and spacing between electrode plates. The optimal combination is:voltage 30 V, electrode plate spacing 50 mm and solution initial hardness 1 000 mg·L^-1. The electrochemical water softening method is suitable for softening circulating water with high hardness. Electrochemical softening water devices should first consider increase of electrolytic voltage and then reduce the spacing between electrode plates.