This standard specifies a method for the determination of ferric oxide content in rare earth concentrates using the potassium dichromate Titrimetric method, which is suitable for rare earth concentrates with ferric oxide content ranging from 0.50% to 10.0%. During the determination process, the sample is subjected to alkali melting and water leaching treatment to filtrate to remove coexisting elements. The acidified filtrate uses tin dichloride to reduce a large amount of iron (III) to iron (II), and then titanium trichloride to reduce the remaining iron (II) to form tungsten blue. Subsequently, in a mixed acid medium, sodium dianiline sulfonate is used as an indicator, and potassium dichromate is used to titrate until the blue color disappears, so as to determine the ferric oxide content. The standard details the required reagents and their preparation methods.