The invention relates to an automatic power supply device installed beside a hot metal ladle car, and the device is disposed beside a parking space of the hot metal ladle car, and is provided with a power supply cabinet. The interior of the cabinet is provided with a switching door mechanism, a press-down and lifting mechanism, an advancing and retreating mechanism, a lifting and falling mechanismand a current collector contact mechanism, wherein each mechanism is driven by a 24V electric push rod to complete the respective motion. The device can be remotely controlled to supply power to thehot metal ladle car at a hot metal ladle car stop. Only the automatic working mode needs to be selected, the device remotely opens a controllable cabinet door and completes the press-down, advancing and rising operations, enables a current collector group in the cabinet to stretch out through a duct and rise to make contact with a sealed power line box of the hot metal ladle car so as to achieve the power supply, thereby completing the supply of power to the equipment on the hot metal ladle car. After power supply, a power supply automatic cut-off mode is selected for completing the falling, retreating and lifting operations, the storage of all mechanisms in the cabinet, and the door closing operation. The device is simple in structure, and is convenient to operate. The motion of all mechanisms is reliable, and the IP level of the equipment is high. The device is especially suitable for the power supply of the hot metal ladle car, and is good in popularization and application prospect.