Abstract: A rapid prototyping(RP) system is presented in this paper.This RP system is based on the tungsten inert gas(TIG) welding deposition technology, which includes a welding electrical source, a TIG welding torch, a wire feeder, a numerical controlled milling equipment, an industrial computer, an AD sampling card and etc.The TIG welding torch and wire feeder were used for weld deposition;the numerical controlled milling equipment was used for controlling the movement of the TIG torch and milling the deposited parts;the industrial computer was used for sampling data and feedbacking control during the deposition process.For resolving the problem of edge sink in weld deposited part, a fuzz control system based on voltage feedback was designed.A wall-shape part was deposited with the help of this fuzz control system.Then a cylinder-shape part with precise geometry size was deposited and milled in the RP system.