The process of laser welding with filler wire (LWFW) is presented to solve the problem of negative reinforcement of thin sheet weld seam, and to satisfy the requirement of high precision assembly in laser self-fusing welding. LWFW experiment about Hastelloy C-276 shielding materials is carried out, and the effects of process parameters on the weld forming are studied. The microstructures, element distribution and micro-hardness of weld joints in different zones are analyzed. The results indicate that the weld joints with controllable positive reinforcements on both top and bottom surfaces by using LWFW can be obtained, and the weld appearance with uniform reinforcements and contact angles on upper and lower surface is available under the optimized process parameters conditions. Obvious grain refinement in weld joint and no obvious heat-affected zone at the junction of base metal and fusion line are observed. The element distribution of weld is uniform in different melting zones, and macro segregation is not found, but micro segregation of Mo in columnar dendrite zone is significant. The micro-hardness of weld joint is well-distributed in different regions and the value is basically equivalent to that of base metal.