Abstract: The weldability was investigated on ultra low-carbon bainitic steel with thermomechanical control process by utilizing shielded metal arc welding, submerged arc welding and welding thermal simulation test.Results showed that hardness is a little different in the heat affected zone (HAZ).The maximum hardness in the heat affected zone was less than 60 HV.Compared with the same class of low alloy high strength steels, the uniformity of strength in HAZ increases remarkably.The heat affected zone has high toughness. The impact absorbing energy at -40℃ reaches above 60 J in the simulated coarse-grained zone when the heat input was 56 kJ/cm.The impact absorbing energy at -40℃ reached above 100 J in shielded metal arc welding, and submerged arc welding.