The invention discloses a transformer parameter estimation method. The method comprises the steps: obtaining an original parameter and remote measurement data of each side of a transformer; carrying out the first-order lag filtering of measurement results when all measurement results are effective; calculating the rated voltages of high-voltage sides of two windings or the rated voltages of high-voltage sides of three windings and the rated voltages of medium-voltage sides of the three windings; and calculating reactance parameters of two windings. The method is good in stability, is simple, and is high in practicality.