The invention discloses a metallographic phase corrosive used for displaying a tempered sorbite tissue austenite crystal boundary and a corroding method. The metallographic phase corrosive comprises saturated picric acid, sodium dodecylbenzenesulfonate and alkanolamide, wherein the corrosive comprises 0.1-15 wt% of the sodium dodecylbenzenesulfonate and X wt% of the alkanolamide, with the balance being the saturated picric acid, wherein the X is any value between 0 and 1 with the 0 and the 1 being inclusive. The metallographic phase corrosive prepared by adopting a formula and through the preparing method can allow the tempered sorbite crystal boundary to be presented clearly and continuously and to be not influenced by tissues, and allows each crystal grain to be clearly observed, thus improving accuracy and precision of judgment. Corrosion is performed at room temperature, is free of heating, wide in corrosion time range, free of over-corrosion, economical, practical, convenient in operation, time-saving, labor-saving, and free of pollution.