Laser hybrid welding has become one of the most promising welding methods used to weld ship thickness steel plates with high efficiency due to combining the advantage of laser welding and arc welding. CO2 laser hybrid welding processes of ship steel plates are studied. The influences of the shielding gas composition on the chemical composition of weld and the distance between the laser beam and arc on the stability of the welding process are mainly analyzed. Based on the optimizing process parameters, 10Ni3CrMoV steel plates with a thickness of 14 mm are welded on both sides in T joint form using high-power laser hybrid welding. The welds produced are assessed by X ray. No crack is found and there is only a small amount of pores. The microstructures of welded joints are examined by optical microscope. The results show that the microstructure of welded joints has good comprehensive mechanical properties. Especially after the weld overlap region experiences a re-melting and heat treatment, the microstructure is refined. The microhardness of welded joints is tested in different regions. The maximum hardness of welded joints is less than 360 HV. The welds obtained can meet the technical requirements for shipbuilding industry.