This standard describes the method for determining the content of working reference reagents using the weighed Titrimetric method. By precisely weighing the mass of the operating solution or reference solution and determining the titration endpoint using the indicator method, it is ensured that the relative standard deviation of the determination result reaches 0.02%. This method is suitable for the accurate content comparison between a standard substance with similar chemical composition and a working reference reagent. When the standard substance and sample can react rapidly and accurately, a reference solution with accurate concentration can be prepared using the weighing method and the content determination can be carried out by the titration method. This standard provides detailed guidance and requirements for the high-precision content determination of working reference reagents.