Abstract: E551T1-Ni2 flux cored wire was used to weld the steels between Q345E and 14NiCrMo10 6V, and then the mechanical properties and microstructure of the welded joints were studied through room temperature tensile, bending, impact and hardness tests as well as metallography analysis. The results show that welded joints with good tensile property, bending property and impact toughness could be obtained using the flux cored wire; the hardness of the weld seam was in the range of 200-250 HV. The microstructure at the grain boundaries in the weld seam was pre-eutectoid ferrite, a little carbon-free bainite which stretched from grain boundaries into the grains, and acicular ferrite and pearlite in the grains, also some granular bainite distributed at individual locations. The microstructure of heat affected zone (HAZ) and weld seam transition area at the side of Q345E steel consisted mainly of block pre-eutectoid ferrite which precipitated along the grain boundaries, and some lath ferrite which stretched into the grains, and small amount pearlite and bainite. While the microstructure of HAZ and weld seam transition area at the side of 14NiCrMo10 6V steel was lath martensite and granular bainite.