Abstract: Many transverse cracks appear in a wire rod for high strength welding wire in the drawing process. The fractured specimens are tested and analyzed by scanning electron microscope and metallographic microscope, direct-reading spectrometer and microhardness tester. The results show that the chemical composition and internal metallographic structure of the fractured welding wire rod are normal, and that the inclusion situation is not serious. The main cause for transverse crack is the martensite structure at the edge. When the welding wire is drawn too fast or the lubrication condition is poor during drawing, heat is generated by friction of contact position the between the welding wire and mould. The austenite transforms at high temperature, and turns to be martensite after being cooling. The martensite has high hardness and brittleness, so transverse cracking occurs under the action of axial tensile stress of wire drawing.