Abstract: In this study, a set of methods for the determination of thiocyanate content in water containing hydrogen peroxide was established. This method innovatively selected manganese dioxide as the catalyst and copper chloride as the promoter to eliminate the interference of related substances in the sample matrix. Under the basic reaction conditions, an additional amount of sodium thiosulfate was added, which could effectively eliminate the background interference caused by the introduction of copper ions due to the addition of copper chloride. In the whole reaction process, manganese dioxide only functioned as a catalyst, and it will not dissolve into the solution system by itself, so there was no need for special design steps to eliminate the possible interference. This method effectively improves the selectivity of determination and enables accurate measurement of thiocyanate. Compared with existing methods, it has significant advantages such as simple operation, low cost and environmental friendliness. It is especially suitable for rapid on-site testing in mining enterprises and routine laboratory analysis, demonstrating good practical promotion value. The relative standard deviation of the determination results ranges from 0.16 % to 1.47 %, and the spike recovery rate is between 97.0 % and 104.5 %. The method features simple operation, low cost and high accuracy.