In this paper,a simple passive network conduction instrument is designed and completed using AT89S52 and FPGA as measurement.Data processing are adopting DFT to complete digital signal processing,using DDS technology,combining with common periphery circuits of I/V conversion and A/D sampler.Moreover,the system also implements the function of continuum measurement,frequency characteristic testing and drawing.The results show that the system has several advantages as followings:steady performance,simple configuration,unique designing thought,high measurement accuracy, convenient operation.