Abstract: The phase morphology and characteristics of as-cast 2507 duplex stainless steel were studied by using optical microscopy, scanning electronic microscopy, energy spectroscopy, X-ray diffractometer, transmission electronic microscopy and micro-hardness tester. The results show that after erosion by the color metallographic erosion agent (1 g Na2S2O5 + 10 mL HCl + 50 mL H2O), the khaki phase of the steel was austenite phase, the yellow-green phase was ferrite phase, and the zebra grain structure was (σ+γ2) eutectid structure.