Abstract: Butt welding was carried out on 15Ni3CrMoV steel and 10Ni5CrMoV steel by TIG(tungsten inert gas) welding and manual arc welding, the microstructure, tensile property, impact property and hardness of the butt joint were studied. The results show that typical dendrite microstructure was found in the weld seam of dissimilar steels butt joint, the grains in weld seam of manual arc welding butt joint exhibit the characteristic of vertical growth, while the grains in weld seam of pulse TIG welding butt joint exhibit the characteristic of horizontal growth. Tensile fracture position of the butt joint at room temperature located in weld seam zone, and the hardness of heat-affected zone is highest. Compared with manual arc welding butt joint, the pulse TIG welding butt joint has higher tensile strength and impact toughness.