Objective A general experiment platform of electrical impedance tomography(EIT) based on field programmable gate array(FPGA) was designed to meet the requirements of EIT digital measurement.A digital current source and the research on digital demodulation method was completed.Methods For construction of the experiment platform,DDS module,D/A and A/D interface module,digital demodulation module and RS-232 communication module were all integrated in one FPGA chip.Results The source can provide multi-frequency excitation signals of 2 mA in the range of 6.1-390.6 kHz.The output impedance of the source was higher than 190 kΩ.Both the real and the virtual information of measured impedance could be extracted.Conclusion Measurements based on bioimpedance-equivalent circuit model verified the validity of the platform.The research results of this paper provides a foundation for the construction of a practical EIT system. Key words: Electrical impedance tomography; Current source; Field programmable gate array; Digital demodulation