Abstract: In view of the problem that 30MnSi coil wire with a diameter of ø12 mm produced by a certain high-speed wire rod unit, when used for processing steel rods for prestressed concrete, some of the rods experienced cracking at the head during the head upsetting process, this paper analyzed the causes of the cracking and proposed corresponding measures by observing the crack morphology, analyzing inclusions, conducting microstructure and composition analysis on the cracked samples. The results showed that the cracking of the head of the steel rods for prestressed concrete was mainly due to the high content of phosphorus and sulfur in the billet, which formed segregation, and during the rolling process, ear defects were generated, causing the rolled products to form folds and loops, and during the drawing and twisting of the spiral ribs, the folds and loops expanded further due to the maximum shear stress, resulting in cracks. At the same time, corresponding improvement measures were proposed for key processes:strictly controlling the composition during the steelmaking and refining processes to minimize the content of phosphorus and sulfur, improving the purity of the molten steel and reducing composition segregation and fluctuations; following the process technical regulations for rolling, reasonably designing the rolls, accurately calculating the reduction and widening, precisely adjusting the roll grooves and guide vanes, reducing or eliminating defects such as ears, burrs, scratches, as well as surface defects such as loops, folds, peeling, and scabs on the finished products; using appropriate lubricants during the drawing process to reduce friction and heat generation, thereby reducing the risk of cracking; before the head upsetting process, the temperature of the end induction heating should be focused on, controlled at (900 ± 20)℃ for the best. After adopting the improvement measures, the cracking of the head of the steel rods for prestressed concrete was eliminated.