Abstract: The spherical VC particles reinforced Fe-C-Cr-V alloy matrix composites were prepared by in-situ reaction casting. The microstructure and phase structure of the composites were observed with the metallurgical microscope, scanning electronic microscope and X-ray energy spectrum analyser. The results show that VC particles in Fe-C-Cr-V alloy containing 7% V are formed obviously above 1680℃. The almost perfect spherical VC particles are obtained at about 1750℃. The spherical phenomenon is not obvious if the holding time is too short. The long holding time would cause coarsening of VC particles. The VC particles could disperse homogeneously in 5 minutes of the holding time. The rare earth or nodulizer can be both useful to promote spheroidizing of VC particles. The formation mechanism of spherical carbonized composites in the alloy system was investigated.