Laser-arc hybrid welding is a promising technology which can be widely used in industry and it attracts attention of the researchers worldwide. Combining two heat sources with different physical properties and energy transmission mechanisms together, laser-arc hybrid welding possesses the composite advantages of laser welding and arc welding. Some aspects on laser-arc hybrid welding such as the laser-arc interaction, droplet transfer characteristics, dynamic behaviors of the keyhole and the weld pool, hybrid welding processes and their applications are reviewed.