In recent years, the power system of the demand is higher and higher, to stable operation of power grids for power transformer substation thermometer temperature measurement accuracy and precision of data demand more and more is also high. At present, the power transformer winding thermometer have a direct measurement and indirect measurement method and thermal simulation measurement. Direct measurement is a direct buried in transformer winding temperature sensors, temperature measuring instrument direct measurement show no winding temperature. Indirect measurement is according to the international electrotechnical commission recommended formula of oil-immersed power transformer winding hot spot, through the calculation of parameters and the transformer load current value calculation method to calculate the winding hot spot temperature is complex, the error is large. In addition, considering the difficulty of the electrical insulation, direct measurement of winding temperature on insulation processing has great difficulty, high cost. So, generally at home and abroad on the principle of the thermal simulation to directly measure temperature of transformer winding. Thermal simulation method of measurement, it is according to the loss of transformer load and load current is proportional to the square, and the development of a winding measurement method. Winding thermometer on the basis of the oil level of the thermostat is equipped with a current verifier and electric heating element, through the transformer winding temperature superposition to reflect the temperature, the temperature measurement method has the characteristics of simple and applicable.