Process wastewater in the gold industry contains metal ions such as copper, nickel, and mercury, whichcause unstable coloration and low determination results when using ferric salt colorimetry. A method for determiningthiocyanate with the removal of copper, nickel, and mercury interference was developed. The addition of N,N-dimethyl⁃formamide addressed the issues of unstable coloration and severe fading within a short time. The interference fromhigh⁃concentration copper ions was eliminated by masking with sodium thiosulfate under alkaline conditions, wherecopper ions were removed as cuprous sulfide precipitate. Meanwhile, sodium thiosulfate effectively masked nickel andmercury ions under acidic conditions. The relative standard deviations of determination results by this method rangedfrom 0.21 % to 1.33 %, with spiked recoveries of 98.0 %-101.3 %. This method offers advantages of simple operation,low cost, high accuracy, and good precision, demonstrating valuable potential for broad application.