Abstract: In order to develop the rapid prototyping technology, cold metal transfer arc welding process was adopted and the corresponding robot rapid shaping system was set up. The effect of welding current, welding velocity as well as the welding process on the aspect ratio of the single pass weld seam(λ) was studied. Besides that, the effect of the welding current, elevating height and welding process on the shaping of multilayer cylinder specimen were further investigated, the optimal shaping parameter was obtained and the tensile property of the specimen was tested. The results show that, the larger aspect ratio of weld seam is benefit to obtain the rapid shaping specimen with the flat surface and better accuracy. Suitable welding parameter and weld process can control the dimensional accuracy of shaping and obtain specimens with high performance.