Abstract: When the α-grain size of surperplastic TC4 titanium alloy plates is too small, the grain boundries would not be displayed effectively by the common etching reagents. The experimental results show that a layer of transparent film could be deposited on the polished surface of TC4 titanium alloy metallographic samples by anodic oxidation coating method or chemical deposition method, and the interference effect of light through the film could display the α-grain morphology vividly, completely and clearly. By these two methods, the metallograph of grain size of TC4 titanium alloy plates which met the superplastic forming requirements was obtained.