The invention relates to a verification device for a thermometer of a transformer, belongs to the field of verification of the transformer thermometer, and solves the problems that a present verification device for the thermometer of the transformer is in accurate in a verification result and low in working efficiency. An adiabatic detection groove is used to accommodate transformer oil; a top cover of the detection groove is provided with a jack of a heating rod, a jack of a probe of the thermometer to be calibrated and a jack of a standard thermometer; a frequency converter is used to drive a motor; the motor provides required mechanical energy for an oil pump; after that the heating rod is started, the adiabatic detection groove, the oil pump, a flow control valve and a first tube form a heating loop; after that a fan is started, the adiabatic detection groove, the oil pump, the flow control valve and a second tube form a cooling loop; a temperature control unit is used to control the temperature of the transformer oil; a power supply module provides needed voltage for different parts; and a power control unit is used to switch ON/OFF the power supply module and control connection between the power supply module and the different parts. The verification device is suitable for onsite verification of the thermometer of the transformer.