Abstract: With the Gleeble 3500 thermal simulation testing machine, the HFW process is simulated to analyze the extrusion temperature, hardness and microstructure of weld zone metal.The test result shows that fluctuations of the extrusion deformation rate and the extrusion strain are mainly related to the phase transition of the weld zone metal during extrusion process and the after-welding cooling process.The higher the carbon equivalent of the tested steel, the higher the initial temperature of the weld zone metal extrusion, whereas the lower the final temperature, which not only affects the welding quality, but also affects the production efficiency.