The utility model relates to an impedance test device for a low voltage electric power carrier channel, which belongs to the field of power grid carrier communication, and aims at solving the problems of the existing method for measuring the carrier channel impedance that the frequency characteristic of a high frequency transformer and a resonant circuit affects the accuracy of the carrier measured value, the frequency point of the carrier measurement is limited, only the impedance magnitude can be measured, and the phase of the impedance can not be measured. The starting carrier control end of an embedded signal acquisition processing system of the impedance test device is connected with the signal control end of a DDS (digital display scope) carrier signal source, the test input and output end of the embedded signal acquisition processing system is connected with the test input and output end of a free coordinate axis vector measuring unit, the DDS carrier signal source, a high frequency power amplifier are sequentially connected with the primary side of the high frequency transformer, a load resistor R is connected between the high frequency power amplifier and the primary side of the high frequency transformer in series, the output end of the secondary edge of the high frequency transformer is connected with the input end of the coupling unit of a detuned circuit, and the output end of the coupling unit of the detuned circuit is connected with two low voltage power lines tested.