Abstract. Injection molding is one of the most important processes in manufacturing nowadays. Thus, attention must be given towards the optimization of the product defects. Parameters have been chosen by screening tests to improve the process quality. The main purpose of this study is to optimize the processing condition using Taguchi Method on shrinkage for HDPE-Clay specimen. The experiment starts by preparing the mixture between HDPE and clay. Then, screening test is conducted to obtain the parameters. The parameters are melt temperature, injection speed, injection pressure and cooling time. By using the array orthogonal L 9 (3 4 ), signal to noise ratio and ANOVA were conducted. Based on the S / N ratio analysis, best combination can be produced for warpage (melt temperature: 190 o C, injection speed: 40%, injection pressure: 30% and cooling time: 3 seconds). While for ANOVA, melt temperature is most significant with 60.28% for warpage.