A direct metal rapid prototyping process based on the plasma arc welding was presented. The effects of 6 important processing parameters, such as pulse current, wire-feeding speed etc, on the ratio of width to height of the deposited track cross-section (λ) was investigated by Taguchi method and temperature contrast experiments. The results show that pulse current, duty circle, wire-feeding speed and scanning speed exert significant influences on λ. The plasma gas flow-rate has a great effect on λ, while pulse frequency has no obvious effects on λ. The tensile strength and density of Ti-6Al-4V parts fabricated with the optimized parameters was tested. The results show their test data is similar to that of the parts fabricated with laser deposited process.