The velocities of particles in Electrorheological (ER) fluids were measured by laser speckle velocimetry. It was verified that laser speckles could be formed by illuminating laser beam on the starch ER fluids. The speckle patterns was recorded with high speed CCD camera, and the speckle patterns sequences with short time intervals was obtained by intercepting laser speckle video. Velocities parallel to the direction of electric field and that perpendicular to the direction of electric field were obtained by processing the two consecutive speckle patterns. The experimental results show that the velocities of particles decreases oscillatorily with time. Furthermore, there is a critical electric field and a critical sample concentration. When it is lower than this critical electric field (particle concentration), the mean particle velocity increases; otherwise, it decreased.