Abstract: A welding method for steel reinforcements, wherein electric current flows through the reinforcements, an electroslag pool formed from a solder melted by an electric arc generates a lot of heat to melt the reinforcements, pressure is applied to combine the same; the method uses a clamping device, wherein a sliding chuck is adjustably rotated by means of a bolt handle thereon to enhance a movable clamping seat to clamp the upper reinforcement, then a fixed chuck is adjustably rotated by means of another bolt handle to enhance another movable clamping seat to clamp the lower reinforcement, a crank provided at one side of a main body can be optionally rotated forwardly or backwardly to raise or lower the upper reinforcement, or the upper and the lower reinforcements can be compressed for combining.