Porous titanium orthopedic implants fabricated by 3D printing have golden prospects. As one of the surface technologies, electrolytic plasma polishing can effectively remove the powder particles attached to the surface of 3D printed porous titanium parts and can reduce the surface roughness. In this paper, the surface morphology and surface roughness of the external and inner surface were analyzed and tested at different plasma polishing times. Electrolytic plasma polishing is effective to improve surface roughness. The longer the polishing time is, the smoother the surface is and the lower the surface roughness is. The polishing time is an important factor affecting the surface roughness. By the fitting curve, the surface roughness of the external and inner surface can be guaranteed to be within a reasonable range by the control of polishing time.