The utility model discloses a 110kV transformer substation cable layer water level monitoring device, which comprises a water level monitoring terminal and a liquid level sensor, wherein the water level monitoring terminal is arranged in a transformer substation cable layer, the liquid level sensor is arranged on a cable layer water pool, is provided with a wireless radiating circuit, a monitoring camera is connected with the water level monitoring terminal through a data communication line, the water level monitoring terminal is provided with a wireless receiving circuit, the liquid level sensor sends monitored water level information to the wireless receiving circuit through a wireless transmission circuit, an alarm is arranged in the transformer substation cable layer, the water level monitoring terminal controls the alarm to call the police when the water level reaches to an alarm value, and sends water level information and video monitoring information to a background monitoring system through a general packet radio service (GPRS) communication module. The 110kV transformer substation cable layer water level monitoring device can prevent the water level of the transformer substation cable layer from being too high to cause risk in time, guarantees real-time monitoring of critical situations of substation operation personal, and effectively guarantees a transformer substation to safely run.