Based on the principle of impedance measurement of currentvoltage method and digital measurement thought, a kind of DSP impedance measurement system is proposed. This system takes DDS signal source as the measurement excitation, sampling the signals at both ends of standard resistance and measured impedance components, and then put the sampled signal into DFT. Finally, the measured signals are separated to false or true through relevant computation and the measurement result is gained. By setting the sample frequency and number, the measurement error caused by the frequency leakage of signal is effectively avoided in the system. Upon the measurement experiment, several reasons for main measurement error and effective method to reduce the error are put forward, and consequently the relative error is kept in ±1%. Compared with the method that applies phase sensitive detector and time to digital converter to measure the impedance, this system ensures the measurement accuracy and significantly simplifies the hardware circuit and software design.