A NiCuFeBSi alloy layer was fabricated by laser cladding on HT250 substrate through a Nd:YAG laser. And each carbon structure in the cladding layer, semi-melt zone and heat affected zone (HAZ) was investigated. Results show that carbon distributes in the cladding layers in the form of graphite, CO and C atom solid soluted in [Ni,Cu]. However, carbon distributing in the semi-melt zone are in the form of Fe3C and micro graphite pebble. And in the HAZ, carbon diffuses around graphite and solid solutes in the acicular martensite due to the extremely high cooling rate of molten pool. Moreover, with increasing of the distance to the bonding interface, the content of martensite decreases gradually. Graphite in the substrate fuses less and keeps to be flake