Ballast water refers to seawater loaded into ballast tanks to balance ships. To prevent marine pollution, the sterilization of ballast water in ships is essential. The methods for sterilizing ballast water include chemical and electrolytic treatments, as well as other methods. The purpose of this study was to improve the efficiency of the electric sterilization method by varying the cross-junction and twisting number of the static mixer elements to investigate their effects on pressure drop and mixing. As a result, when the twisting number of static mixers was high, the shape of the cross-junction static mixer elements yielded a higher pressure drop than that of the continuously bonded elements but with a lower vorticity. When the twisting number of the static mixer was low, there was no significant change in the pressure drop or vorticity, regardless of whether the elements were crossed. Because it is believed that the pressure drop will have a greater impact than vorticity on the mixing of seawater within the pipe, a static mixer with a high twisting number and cross-junction elements is considered the most suitable shape.