This invention involves a ratio of the rate of zero-sequence direction relay measurement reactor inter-turn fault method, including the following steps: a. movement of tectonic relay function F1 constructed relay system Momentum function F2 ; b. Order F3 = F1 - F2; c. Measurement Reactor zero-sequence current I0 and into the function F; d.; judgment whether F3 >= 0 E. When F3> 0:00, concluded that inter-turn reactor fault relay action. By analyzing the invention reactor malfunctions zero sequence voltage and zero-sequence current phase, the rate of tectonic than zero sequence direction of Relay equation and tectonic movements than fixed-rate zero-sequence direction relay braking capacity equation, the method can Relay in a reactor internal inter-turn brake failure zero, movement of largeexternal reactor in single-phase ground fault occurred when braking tremendous volume of movements of zero, so as to solve the reactor failure in the inter-turn the sensitivity and reliability problems.