Abstract: Polystyrene/carbon fiber (PS/CF) composite powders were prepared by using polystyrene (PS) as matrix material, and then the SLS parts were prepared with this composite powders at a preheating temperature of 80 ℃ with a laser power of 30 W and a delamination thickness of 0.25 mm. The effects of particle size and content of matrix material on the mechanical properties and precision of SLS parts were studied intensively. The results indicated that the particle size of the composite powders met the requirement of SLS technology. When the mean particle size was 75 μm and the PS/CF mass ratio is 9∶1, the fusion effect between PS and CF was optimal. The bending, tensile and impact strength of the sintered parts reached 6.88 MPa, 2.97 MPa and 2.98 kJ/m2, respectively, and meanwhile their absolute dimensional deviations were only 0.8 %, 0.22 % and 1.6 % in x, y and z directions, respectively. Compared to the sintered parts made from pure PS under the same condition, the sintered parts made from the composite exhibited an increase in bending strength by 62.06 %, in tensile strength by 74.29 % and in impact strength by 83.95 %, and their dimensional accuracy increased by 5.44 %, 69.44 % and 81.34 % in x, y and z directions, respectively.