The effects of the mold temperature and the forming speed on semi-solid 6061 alloy forging were studied by means of software DEFORM-3D. The results show that when the temperature of semi-solid slurry is kept at 650 oC, the mold temperature 400 oC, and the forming speed 50 mm/s, an excellent part can be obtained. The HV hardness value of semi-solid forging parts with T5 treatment is 2166 MPa, 170.5% higher than that of the normal low-press cast parts. The simulation results are well in agreement with the experiment.