The invention discloses a measurement method and system of interphase leakage magnetic fields of transformer windings. The measurement system of the interphase leakage magnetic fields of the transformer windings comprises a power supply, transformer windings electrically connected with the power supply, a short circuiting device communicated with lines between the power supply and the transformer windings, magnetic induction sensors arranged in middle positions of adjacent windings of all transformer windings and used for inducing the leakage magnetic fields between the adjacent windings, an electromotive force measurement device electrically connected with the magnetic induction sensors, as well as a magnetic density calculation device electrically connected with the electromotive force measurement device. By means of the technical scheme, the accuracy of the leakage magnetic fields can be improved.