A direct metal rapid prototyping process based on the plasma arc welding is presented. The impacts of six important process parameters, such as pulse current, wire-feeding speed etc, on the ratio of width to height of the deposited track cross-section (λ) is investigated by Taguchi method and temperature contrast experiments. The experimental results showed that pulse current, duty circle, wire-feeding speed, scanning speed exert significant effects on λ. The plasma gas flow-rate has significant effect on λ, and pulse frequency has not significant effects on λ. The tensile strength and density of Ti-6Al-4V part fabricated with the optimized parameters is tested. The results show the test data is similar to the parts fabricated with laser deposited process.