Abstract: Based on the demand that measurement and control System is low power consumption,high precision and miniaturization,this design has analyzed the requirements of power system harmonic measurement and the characteristics of AD574A at first,then hardware design of sampling circuit is realized with the platform of Altera's DE2 board,and at the same time the interface design of AD574A and Field Programmable Gate Array(abbreviation-the FPGA) is completed in Quartus II,a AD sampling experiment is done under the program configuration at last,the correct ness of the method is proved by experiment.