A method and apparatus are disclosed for automatic optimization of Doppler imaging parameters. The method includes obtaining and storing at least two characteristic spectral lines at a predetermined pulse repetition frequency. The method further includes optimizing at least one of the Doppler imaging parameters based on the stored at least two characteristic spectral lines and a predetermined mean noise power. In one embodiment, the characteristic spectral lines are obtained by collecting in real time the Doppler spectral lines generated at the predetermined pulse repetition frequency within a predetermined time period, and processing the collected Doppler spectral lines in real time without storing them.