Spectrum analysis of harmonic signal is an important task in the harmonic detection of power system and the accurate harmonic detection is the precondition of maintaining normal operation of the power network. For the achievement of real time output of harmonic spectrum

the base 2-FFT algorithm based on FPGA chip and extracted in accordance with frequency is designed. The complete design is subject to modular design based on the Verilog language

the Stratix II series FPGA chip is used as the logic controller and the simulation verification is performed by the Quartus II and Matlab software simulation tool. The simulation result shows that the system can real-time detect harmonics accurately and has a certain practical value for the harmonic analysis and operation of power grid.