The invention discloses a method for an optical current transformer to carry out high-speed measurement, and the method comprises the steps: carrying out the high-frequency modulation of an optical signal in an optical fiber through a modulator, wherein the modulation frequency is an uneven number of times of intrinsic frequency of the optical current transformer, wherein the uneven number is not less than three; achieving the increase of the maximum sampling rate of an optical CT in a mode of uneven frequency doubling modulation under the condition that the total length of the optical path is not changed, and reducing the data time delay of the transformer, thereby meeting the demands of high-speed measurement of the optical current transformer.