A method of pedestal component elimination is proposed using line CCD for spatial-filter velocimetry (SFV) signal, which is based on spatial filtering effect of line CCD. By using difference demodulation arithmetic, pedestal and direct current (DC) components are eliminated, both amplitude and signal noise ratio are improved at the same time. Characteristics of equivalent difference spatial filter are analyzed with the research of power spectral density function of spatial filter difference demodulation. The feasibility of pedestal component elimination using difference demodulation arithmetic is validated with experiments. The result shows that difference demodulation arithmetic can eliminate pedestal and DC components, and amplitude of signal component is doubled, which will benefit the pick-up of useful signal component.