Medium plays an important role in the laser and fluid corrosion combining processing. Through X-ray diffraction analysis of chemical composition on the tool steel surface after laser-chemical processing, its chemical resultant is researched and analyzed. And the chemical reaction process of the laser and chemical hybrid etching of the tool steel material is explicated. Applied electron microscopy to surface morphology observation, under the action of laser beam, the effect of different chemical media corrosion on tool steel material is studied. The chemical mechanism of material removal of combining processing of laser and chemical corrosion on tool steels is discovered.