This standard specifies a method for determining the content of hexavalent chromium ions in powdered chrome tanning agents. It is suitable for powdered chrome tanning agents made of sodium dichromate as raw material after acidification and reduction treatment. The method reacts hexavalent chromium ions with diphenylcarbazide to form a purplish-red complex, and uses Spectrophotometric method, spec-trophotometry for quantitative determination. The standard describes in detail the required reagents, materials and devices, which provide a scientific basis for the accurate determination of hexavalent chromium ions in chrome tanning agent products and ensure the safety and environmental protection requirements of the products in the tanning process.