The invention discloses an interturn protection method of a high-voltage shunt reactor based on parameter unbalance detection, which is established on the basis of a time domain parameter model and comprises the following steps: calculating the electrical parameter of each phase under the least square significance by using the electrical quantities at the initial end and the tail end of the high-voltage shunt reactor; and identifying whether the interturn short circuit fault of the high-voltage shunt reactor occurs or not by constructing the comprehensive criterion of the parameter unbalance detection under the condition that the interturn short circuit faults of the three phases of the high-voltage split-phase shunt reactor can not occur simultaneously. The interturn protection method can not be influenced by system oscillation and frequency shift. The method is based on measurement and comparison of equivalent inductance parameters of each phase of the reactor, thus the setting process is simple and convenient, and the sensitivity is higher. Because the interturn protection detects the changes of each phase of the inductance parameters, the influence caused by system operation modes and faults on the basis of the sequence component detecting principle is avoided, and the interturn protection method can automatically adapt to the change of the installation position of a voltage transformer.