A cooling structure for a hybrid powertrain apparatus of a vehicle may include: a first rotor shaft coaxially connected to an engine output shaft and connected to a rotor of a first motor; an engine clutch shaft coaxially connected to the first rotor shaft not to rotate and connected to an engine clutch; a transmission input shaft mounted coaxially with the engine clutch shaft not to rotate by a rotor of a second motor connected to the engine clutch; and a cooling channel formed in the transmission input shaft to be able to supply oil for simultaneously cooling the first motor, the second motor, and the engine clutch.