The invention provides a method for processing a signal. The method includes the steps of conditioning the original signal according to preset conditioning conditions to obtain an analog signal; carrying out A/D conversion on the analog signal to obtain a digital signal; carrying out spectral analysis on the digital signal with an FIR algorithm and an FFT algorithm to obtain a first signal; correcting the frequency and the amplitude of the first signal with a preset correcting algorithm to obtain a second signal; compensating for the amplitude of the second signal according to a preset compensation rule to obtain a third signal, and outputting the third signal to a calculation device. By means of the method, after spectral analysis is carried out on the digital signal with the FIR algorithm and the FFT algorithm, the frequency and the amplitude are corrected, and the amplitude is compensated. The signal is corrected, spectrum leakage of the FFT algorithm is reduced, and meanwhile the picket fence effect of the FFT algorithm is buffered; amplitude compensation is carried out on the signal, FIR band-pass fluctuation and transition band attenuation are overcome, and the accuracy of the signal processing result is improved.