The reduction of gold ions from HClNaClO3 leaching solution with oxalic acid was performed. It was found that, for 50 mL of gold-containing leaching filtrate, 20 mL of 6% (w/v) oxalic acid was required to achieve a selective and effective reduction of gold ions. The reaction temperature and time were found to have significant effects on gold reduction, and the optimal values were determined to be 85 degrees C and 2 h, respectively. The reduction of gold increased with increasing agitation speed and speed of addition of oxalic acid, and the optimal values were 180 rpm and 1.740 mL/min or more, respectively. Under the optimal conditions, the reductions of Au3+, Cu2+, Fe3+, Pb2+, Ag+, and Si4+ were 95.56%, 0.66%, 2.33%, 1.40%, 0.70%, and 0.50%, respectively. The appropriate solution acidity and solution potential, which are two important conditions for achieving the selective reduction of gold ions, were about 623 mV and 2.33.3 M, respectively.