About the analysis of audio signals, an approach to calculate the spectrum of signals based on FPGA is introduced in this paper, and the design is based on Fast Fourier Transform (FFT) and coordinate rotation digital computer (CORDIC).The architecture and implementation of 4096point fixedpoint FFT and the calculation of modulus of complex numbers based on CORDICis presented. To verify resolution and accuracy of the hardware system, the simulation result in Modelsim is compared with MATLAB, and relative error of this spectrum analysis method is 411%.MCU is used for sampling and AD conversion and sending data to FPGA via SPI, to compute the spectrum. When sampling frequency is 60 kHz, the analysis range of the system is 14.65 Hz to 30 kHz, and the system reaches 14.65 Hz frequency resolution. This hardware system is tested through spectrum analysis experiments, and successfully implements computation of spectrum of audio signals.