This paper introduces a novel economical direct metal forming process, which combines of traditional plasma welding processes and layer manufacturing process to fabricate sound metal part. As high heat inputs during welding could affect parts surface quality, a CCD visual monitoring system was used to monitor the process. To avoid the interferer from plasma arc light, the spectrum of plasma arc was measured and analyzed, and a narrow band filter system was designed. The images of molten pool were analyzed, and a fuzzy-PID controller was used to control the molten pool size. Experimental results prove that using this system can improve parts surface quality.