The study established a spectrophotometry method to determine the thiocyanate radical ions in gold smelting waste solutions and optimized the conditions such as the pre-treatment and color-developing time.The results show that during the pre-treatment,the addition of 10 mL 50 g/L sodium thiosulfate solution and 4 mL (1＋3) hydrochloric acid can effectively precipitate and separate interference elements,and the optimal color-developing time is 60 min.The precision of the method is 0.57 %-5.07 %.The recovery rate of the reference material is 96.0 %-102.3 %.The accuracy and precision are both good.The method meets the requirements for thiocyanate radical ions detection in gold smelting waste solutions.