The invention relates to a resistance optimization selection method for restraining DC bias current. The method comprises the following steps: building a simulation model, modeling a calculation gridframe, and calculating the distribution of the DC current in each substation; Select the substation whose DC current is more than 10A to carry out DC bias treatment; the selected substation neural point is serially connected with the 3 omega small resistor, According to the principle of single variable, the resistance of one substation is changed to 3.5 omega at a time, and the sensitivity to thebias current of other substations is obtained. The sensitivity of each substation is sorted in turn, and the series resistance of substation is selected in the order of sensitivity from high to low, and the small resistance of neutral point series connection of each substation is finally determined. The invention can reduce the mutual interference of the series connection resistors of the neutralpoints of each substation, and reduce the total bias current flowing into the AC power network.