A cooling system is used for cooling an electronic apparatus in an electronic device. The electronic device includes a top wall, a bottom wall, a first sidewall, and a second sidewall. The electronic apparatus is supported on a middle of the bottom plate. The cooling system includes an evaporator, a fan, a condenser, a heat sink attached to the condenser, and a refrigerant pipe connected between the condenser and the evaporator. The heat sink and the condenser are set on an inner surface of the first sidewall. The fan is set on the first sidewall and aligns with the heat sink. The condenser operates to cool refrigerant and transfers the cooled refrigerant to the evaporator. A first airflow cooled by and coming from the evaporator flows through the electronic apparatus and the condenser to cool the electronic apparatus and the condenser, and is then vented through the fan.