The invention relates to a method for testing accuracy of an optical fiber current transformer. The optical fiber current transformer comprises an optical fiber ring, a preposed gathering module and a merging unit which are sequentially connected. The testing method comprises the steps that 1) a boost converter applies primary current on the optical fiber ring of the optical fiber current transformer and outputs the current for the second time through a proportioner; 2) the date output by the merging unit and the analog quantity of the secondary output current of the boost converter are simultaneously introduced into a transformer calibrator for verification. Compared with the prior art, the method has the advantages of high measuring accuracy and high measuring efficiency.