Provided is a transformer-monitoring apparatus based on thermoelectric conversion energy acquisition. The transformer-monitoring apparatus comprises a thermoelectric power generation sheet, heat-dissipating fins, a heat-dissipating fan, a voltage modulating circuit, a rechargeable battery, a voltage-stabilizing circuit, a vibration-measuring circuit, a signal modulation circuit, a signal acquisition circuit, a controller, a communication module. A power system of the transformer-monitoring apparatus is formed by the thermoelectric power generation sheet, the heat-dissipating fins, the heat-dissipating fan, the voltage modulating circuit, the rechargeable battery, and the voltage-stabilizing circuit. The voltage output generated by the thermoelectric power generation sheet is connected with the voltage-stabilizing circuit and is connected with the rechargeable battery via the voltage-stabilizing circuit. A large amount of thermal energy is generated when a transformer operates. The thermal energy generated by the operating transformer is directly converted into electric energy by the thermoelectric power generation sheet and the electric energy is used for powering the transformer-monitoring apparatus. The transformer-monitoring apparatus is easy and convenient to install and maintain, cannot influence the normal operation of a power grid, does not require an external power supply, and is suitable for the work environment of distribution rooms.