This study investigated the changes of antioxidant activity and ${alpha}$-glucosidase inhibitory effect of Jerusalem artichoke (Helianthus tuberosus) 100% methanol extracts by various heat treatment. The contents of total phenolic and flavonoid compounds in methanol extract tended to increased gradually with the rise of temperature to 180$^{circ}C$. The maximum yield of gallic acid (51.52 ${pm}$ 2.17mg/g extract weight) and quercetin (13.39 ${pm}$ 0.03mg/g extract weight) were obtained with extraction temperature of 180$^{circ}C$ for 120min. In addition, the improving extraction efficiency resulted in the increased biological activities, such as electronic donation ability (EDA, 90.36${pm}$ 0.57%), reducing power (Abs 1.14) and ${alpha}$-glucosidase inhibitory effect (92.14 ${pm}$ 1.14%). Overall, the results of this study indicate that the optimum conditions for the extraction process were an extraction temperature at 180$^{circ}C$ for 120 min, and will provide the basis for future research on the improving extraction yield of phenolic and flavonoid compounds.