Injection molded plastic parts have many surface detects: weld line, sink mark, flow mark, gloss, shading, scratching, and so on. Because these surface faults have not been accepted esthetically, plastic parts are Produced through painting or texturing. The purpose of this paper is to develop a paintless molded part of TV Mask Front by flow control method and gas-assisted injection molding. In order to minimize defects from injection molding, this study was carried out using computer aided injection mold filling simulations using MF/FLOW and MF/GAS. Based on these numerical results, we developed FR(Flame Retardant) HIPS and established guidelines of part design, mold design, and Processing conditions. We have achieved of cost sayings, improvement of productivity, and utilization of recycling by eliminating surface defects and painting process.