In this paper, orthogonal experiments are used to study the effects of the four parameters of laser power, scanning speed, powder thickness, and scanning spacing on the surface roughness and side roughness of TC4 titanium alloy molded parts during the rapid prototyping by laser melting and the influence law of surface hardness. Results show that the important order of the four parameters on the upper surface roughness is laser power, scanning speed, coating thickness, and scanning distance, and the important order of influence on the side surface roughness is laser power, powder thickness, scanning speed, and scanning spacing. The important order of influence on surface hardness is laser power, powder thickness, scanning spacing, and scanning speed. Experimental results show that the optimized process parameters for forming the surface quality of TC4 molded parts are laser power 200 W, scanning speed 600 m/s, spreading thickness 0.04 mm, scanning distance 0.06 mm.