In the steel-work the rolled coils of low carbon steel plates must be unended before pickling on the continuous mill. This was solved with butt welded joint by laser beam welding at ISD DUNAFERR Dunai Vasmő ZRt. The 8 kW light power, near TEM00 mode laser beam’s final part of optical system is a divided parabolic mirror, which creates two focal spot in the welding region. In the interest of productivity rising, the rolled bands’ ends have to be welded at the highest speed as far as possible. The welded seams have to tolerate the repeated bends on the pickling mill without cracking. The optimum parameters of laser welding technology were determined by metallography and calculation of energetic efficiency.