A thermal management system for an electric vehicle includes an interior air conditioning part including an air inflow part, an air discharge part, a cooling core, a heating core arranged between the cooling core and the air discharge part, and an adjustment door. The adjustment door is selectively adjustable to control whether air from the cooling core may flow into the heating core. A heat transfer line connects an electric part core to the heating core for transferring that heat of the electric part to the heating core, in order to allow heat dissipation of the electric part through the heating core.