Present application provides a method for suppressing noise in a spectral Doppler system, comprising the steps of: obtaining a power spectrum of Doppler signals demodulated in the spectral Doppler system, by performing spectral analysis on the Doppler signals; estimating an average noise power of the spectral Doppler system; designing a noise suppression filter by determining its filter coefficients based on the power spectrum of the Doppler signals and the estimated average noise power; filtering the Doppler signals by using the designed noise suppression filter so as to reduce the noise.