The invention relates to the field of detection pretreatment, and in particular relates to a treatment method using flouroantimonic acid for digestion of trace impurity elements contained in high-purity chromic oxide. After the chromic oxide is digested with the high-purity flouroantimonic acid, impurities are released from crystal lattices and boundaries, non-volatile impurities are retained after high-temperature volatilization of fluorine and antimony, and non-antimony and non-chromium elements are quantified after reconstitution with nitric acid. The method has an obvious digestion effecton the chromic oxide, has a good enrichment effect on the contained impurities, facilitates use ICP-MS or ICP-AES detection, improves the accuracy of instrument detection results and shortens the detection time.