Phenolic compounds are found in plant materials and regarded as an important human dietary element with a wide range of biological activities and health benefits. Extraction of phenolic compounds can be done by various extraction methods and conditions, but the phenolic compounds yield will be affected by many factors. Therefore, the aim of this study is to evaluate the effect of three parameters (solid-to-solvent ratio, extraction temperature, extraction time) on total phenolic compounds (TPC) yield, and to optimize the extraction conditions for phenolic compounds extracted from cassumunar ginger. In this study, ethanol extraction assisted by water bath shaker was applied for the extraction of phenolic compounds using different levels of solid-to-solvent ratio (1/5 to 1/15 g/ml), extraction temperature (30 to 70 C) and extraction time (30 to 180 min). While, response surface methodology (RSM) with Box-Behnken design was utilized for the optimization of extraction condition. The results showed the three investigated factors significantly affected TPC yield (p-value < 0.05). TPC yields were increased as the function of solid-to-solvent-ratio and temperature, but the TPC yield tended to be stable at prolong extraction time from 105 to 180 min. However, the optimum extraction condition of phenolic compounds extracted from cassumunar ginger was at solid-to-solvent ratio of 1/15 g/ml, extraction temperature of 70 C, and extraction time of 143.5 min. These results are useful by providing the optimum condition for phenolic compounds extraction from cassumunar ginger rhizome and other rhizomes, and useful data for developing extraction process.