The invention provides a TiAl based alloy metallographic specimen corroding method. The method comprises the following steps: kibbling and polishing a TiAl based alloy specimen on silicon carbide paper, and then carrying out electrolytic corrosion, wherein the metallographic specimen to be observed is utilized as an anode, a stainless steel sheet is utilized as a cathode, an electrolytic corrosion solution is utilized as a conducting medium, the electrolytic corrosion voltage is 15-18V, and the electrolytic corrosion time is 30-240s; then washing clean and blow-drying; and observing a clear TiAl based alloy microscopic structure under an ordinary light microscope bright field image condition. The method provided by the invention has the advantages of solving the problem of difficulty in display of the TiAl based alloy metallurgical structure, enabling the to-be-observed surface of the specimen to form megascopic color, integrally and clearly displaying TiAl based alloy structures in different states, obtaining clear and beautiful images by virtue of observation under an ordinary optical metalloscope, enabling grain boundaries in the alloy to be clear and visible and integrally displaying the internal structure characteristics of grains. The method is simple and convenient to implement and does not need special equipment. Compared with other chemical metallographical corroding methods, the method provided by the invention has the advantages of easily controlled conditions, simplicity in operation and good experiment repeatability.