The series reactor can limit the short circuit current of the power grid,but it also brings challenges to the relay protection.An improved setting method for the distance protection of transmission lines with series reactor is presented.The compensation coefficient of zero sequence current is adjusted according to the series reactor's impedance and line's impedance.The distance protection settings are calculated according to the series reactor's impedance and the original distance protection impedance.The improved setting method can guarantees the reliability and sensitivity of distance protection just by modifying the settings and without changing the code.The simulation results demonstrate the effectiveness of this method.