Fresh or dried fruit of Terminalia chebula Retz. is commonly used as herbal medicine as it contains various phytochemicals including gallic acid (GA), ellagic acid (EA), and corilagin (CG). These polyphenolic compounds also exhibited therapeutic properties such as antioxidant, anticarcinogenic, and antimicrobial activities. This study investigated the extraction of polyphenolic compounds such as gallic acid, ellagic acid, and corilagin from T. chebula fruits by subcritical water extraction (SWE). We examined the effect of extraction temperature (120-220℃) and water flow rates (2-4 ml/min) at the pressure of 4 MPa on the amounts of compounds extracted and determined the suitable conditions for SWE of these compounds. In addition, the total phenolic contents and antioxidant activities of the extracts were analyzed and compared to those obtained by water extraction and soxhlet extraction. The results showed that the amount of GA and EA increased with an increase in temperature up to 180℃, where the maximum amounts were obtained. The temperature higher than 180℃ caused the loss of these products due to thermal degradation. For CG, the degradation was also observed and it occurred at even lower temperature (>150℃). In addition, flow rate was found to affect the extraction behavior. At a fixed temperature of 180℃, gallic acid and ellagic acid increased with an increase in volumetric flow rate up to 4 ml/min. For corilagin, the highest amount of this extract is obtained at 3 ml/min. Compared to other conventional extraction methods, SWE could extract higher amounts of products. Moreover, although higher temperature of SWE caused lower total phenolic contents, the extracts obtained by SWE indeed had higher antioxidant activities than those obtained with conventional methods. It can therefore be concluded that SWE could effectively extract a considerable amount of phenolic compounds from T. chebula fruits with high selectivity and quality, and the suitable condition was at temperature of 180℃ and water flow rate of 4 ml/min.