Abstract: Disclosed is an integrated expansion kettle, including a kettle body, a coolant flow channel passing through a chamber is provided inside the kettle body; at least one group of gas-liquid separation mechanisms is provided on the coolant flow channel; each group of the gas-liquid separation mechanism includes a first opening provided on the coolant flow channel for liquid in the chamber to flow into the coolant flow channel and a second opening for liquid in the coolant flow channel to flow into the chamber, and a pressure at the first opening is greater than a pressure at the second opening. A cooling system is also disclosed, which includes a motor cooling circuit, a battery cooling circuit and the expansion kettle. A vehicle is also disclosed, which includes the cooling system.