Laser cladding of SAE1045 carbon steel with SiC/Cu alloy powder was performed in air. The microstructures of the cross-section of the clad layer obtained were obviously divided into three laminae. Analysis results using X-ray diffraction, scanning electron microscope (SEM) and electron probe microanalysis (EPMP) indicate that there exist alpha -Cu, SiO2 and Cu5Si in the top layer. However, SiC particles (SiCp) originally added almost disappeared during laser cladding. To simulate the reaction taken place in the laser pool, differential thermal analysis was carried out by using a Perkin-Elmer DSC 7 in an atmosphere of Ar and O-2. This revealed that the SiCp is stable during heating in the atmosphere of Ar. However, intensive oxidation and decomposition of the SiCp were found when heating was undertaken in an O-2 atmosphere, which reasonably explains the formation of SiO2 and Cu5Si in the top layer.