The invention discloses a liquid cooling high-power charging device and a monitoring method of the liquid cooling high-power charging device. The liquid cooling high-power charging device comprises charging cables, a charging controller and a cooling system. One end of each charging cable is connected with a charging gun. Each charging gun is provided with a thermal sensor. The cooling system comprises an oil tank, an oil pump and a heat dissipater, the oil tank, the oil pump and the heat dissipater are connected with the charging cables through pipelines, and a cooling loop is formed. The thermal sensors are connected with the charging controller and used for detecting the working temperatures of two terminals of the charging guns. The charging controller judges whether the working temperatures are larger than a first preset temperature threshold value or not, and if the working temperatures are larger than the first preset temperature threshold value, charging current is reduced to the preset current range or charging is stopped. By the adoption of the technical scheme, the reliability of the liquid cooling high-power charging device can be improved.