Carbon and SiC doped MgB2 bulk and wires were fabricated by a two-step reaction method. The MgB4 samples were sintered at 900 ℃ for 2 h in closed argon atmosphere, and then appropriate amount of Mg powder was added with the ground MgB4 powder to get MgB2 samples, which were sintered at 750 ℃ and 2 h for bulk samples or 680 ℃ and 2 h for wire samples in closed argon atmosphere. Carbon and SiC doped MgB2 samples were also prepared by solid state sintering for compared. The phase evolution and microstructure of MgB2 samples were characterized by means of X-ray diffraction (XRD) and scanning electron microscope (SEM). The SEM results indicate the porosity of MgB2 samples prepared by the two-step reaction method improves obviously. The carbon doping could effectively introduce the doping element into the MgB2 crystalline lattice and grain boundaries compared with SiC doping.