The effects of Ti3SiC2 doping on lattice parameter (a), microstructure, critical temperature (Tc) and critical current density (Jc) of MgB2 superconductors were studied. Carbon substitution for boron could be confirmed by the shrinkage of the lattice parameter a with increasing of Ti3SiC2 doping level. A reduction of Tc from 37.15 K to 36.55 K with increasing of Ti3SiC2 doping was observed. The Jc values were determined by M-H hysteresis loops. Results show that in low magnetic field region, the Jc value for the undoped sample is higher than those for the doped samples. However, with the increase of the magnetic field, the Jc for the properly doped samples will be enhanced.