The invention relates to a metallographic corrosive for super austenitic stainless steel and a corrosion method. The corrosive is prepared from the following components: 2-10 weight parts of oxalic acid, 80-150 volume parts of concentrated hydrochloric acid and 0-50 volume parts of deionized water. The corrosion method comprises the following steps: S1, uniformly adding oxalic acid, deionized water and concentrated hydrochloric acid according to a ratio, uniformly stirring, and standing for an hour or longer; S2, preparing a metallographic specimen; and S3, taking the metallographic specimen as an anode, taking a highly corrosive metal material as a cathode, immersing into a corrosive, electrifying and corroding; and immediately taking out and cleaning the metal material after corrosion completion, and blowing. The corrosive disclosed by the invention is simple in composition, easy to prepare and recover, safe, environmental-friendly, capable of being repeatedly utilized and cost-saving; the corrosion method is easy to operate, accurately controllable, stable, high-efficiency and excellent in reproducibility; and the corroded specimen is clean, neat, clear and uniform in metallographic structure and excellent in corrosive effect. The metallographic corrosive disclosed by the invention is applicable to metallurgical structure analysis of multiple states such as various super austenitic stainless steel cast conditions, hot working, ageing, heat treatment, welded and the like, a one-dosage multi-purpose effect is achieved, and time and labor can be saved.