Metal ingot casting mold cooling system capable of achieving automatic demolding

A mold cavity and a hollow interlayer are arranged in a mold body, a hollow pin is arranged in the mold cavity, the bottom of the hollow pin communicates with the hollow interlayer, an insertion pipe is arranged in the hollow pin, and the lower portion of the insertion pipe penetrates through the bottom of the hollow interlayer. The hydraulic ejection mechanism is fixed below the mold body, and an ejection rod is arranged in a through hole I penetrating through the bottom of the mold cavity; the two ends of the insertion pipe are communicated with the hollow interlayer and the mold water outlet respectively, the mold water inlet in the lower portion of the hollow interlayer is connected with an electromagnetic valve I and a flow meter I which are connected with a PLC in series, and the PLC is connected with an alarm device. Cooling water in the hollow interlayer is discharged through the insertion pipe inserted into the hollow pin, it can be guaranteed that the hollow interlayer is filled with water, the wate