Abstract: X80 pipeline steel was simulated by Gleeble 3500 thermal simulation test machine, the simulated welding heat affected zone continuous cooling transformation (SHCCT) curve of X80 pipeline steel was formulated, and the changes of microstructure and hardness with cooling rate were analyzed. The results show that the cold crack sensitivity index of X80 pipeline steel was less than 0.2%, which had low welding crack sensitivity. The preheating temperature of welding process should be controlled above 47 ℃, and welding at fast cooling rate should be avoided. According to the preliminary inference of impact absorbed energy and SHCCT curve of X80 pipeline steel after thermal simulation, the more reasonable heat input during welding of X80 pipeline steel was 10-20 kJ·cm^-1.