A powertrain-cooling system of a hybrid vehicle may include an electric oil pump, a pressure control valve, which includes an input port receiving fluid discharged from the electric oil pump, an output port outputting the fluid to a transmission while adjusting the pressure of the fluid, and a drain port discharging a portion of the fluid in accordance with adjustment of the pressure of the fluid, a first motor cooling path connecting the drain port of the pressure control valve to a first motor forming a hybrid powertrain, and a controller electrically connected to the electric oil pump and configured for controlling the electric oil pump to cool the transmission and the first motor.