The invention discloses a high-voltage current transformer leakage current and error measuring method and system. The method comprises the steps of: obtaining leakage currents of a high-voltage current transformer to be tested under a plurality of test high-voltage voltages; obtaining errors of the high-voltage current transformer to be tested under the plurality of test high-voltage voltages; performing model training according to the leakage currents, the errors and corresponding test high voltages of the high-voltage current transformer to be tested to obtain a leakage current error mappingmodel of the high-voltage current transformer to be tested under the high voltage; and obtaining corresponding errors according to the obtained leakage currents of the high-voltage current transformer to be tested and the leakage current error mapping model. The method and system only measure the leakage current to obtain the corresponding errors in the following error monitoring to obtain accurate errors through measurement with no need for improvement of a high-voltage current transformer without a capacitance shielding structure and with no need for direct error measurement under the highvoltage so as to ensure the cost saving while test safety.