The invention discloses a frequency conversion control method for a power transformer cooler, and the method comprises the steps: analyzing an oil flow path and an oil heat dissipation rule through the main transformer forced oil circulation air cooling technology, analyzing and obtaining a main transformer insulating oil heat releasing equation, providing a theoretical basis for the building of atransfer process, carrying out the digitalized programming of a quantitative relation between the temperature t2 of upper oil and the output power of the cooler, obtaining a frequency f2 under the temperature of t2, downloading the frequency f2 to a controller, and enabling the controller to control a frequency converter to change the frequency according to a preset algorithm, thereby achieving the control of the oil temperature of the upper oil of a main transformer and the precise frequency conversion of the frequency converter.