The utility model relates to a high-voltage power transmission line zero-sequence impedance measuring circuit, which comprises parallel three-phase leads, an adjustable voltage source, a voltage transformer, a first measuring device, a second measuring device, a data processing unit, a first current transformer, a second current transformer and a voltage division processing circuit, wherein head and tail ends of the three-phase leads are interconnected; the first current transformer is connected to the tail ends of the three-phase leads in series, and the other end is connected with the data processing unit through the second measuring device; the second current transformer is connected to the head ends of the three-phase leads in series; the adjustable voltage source is connected to the head ends of the three-phase leads; and an input end of the voltage transformer is connected to the middle parts of the three-phase leads, and an output end is connected with the first measuring device. The high-voltage power transmission line zero-sequence impedance measuring circuit is modified through measuring average values of the voltage division processing circuit on both ends of a power transmission line, eliminates the influence on the measurement of zero-sequence parameters of distributed capacitance on the power transmission line, and greatly increases the precision of measurement results of the zero-sequence parameters of the power transmission line.