Abstract: Two-dimensional frequency shift laser Doppler velocimetry (LDV) is used to measure the instantaneous velocity of suspended particles in oil, according to four different situations of suspended particles going through the pinhole aperture of LDV. The original processing method of instantaneous velocity of suspended particles LDV is improved, an analysis processing method is proposed. The improved method shows better stability in measuring the instantaneous velocity of suspended particle, it can characterize the change trends of particle group with time when a group of particles are passing through the pinhole aperture in LDV, and it enhances utilization efficiency of the sampling data of the frequency shift LDV. This method further accurately characterizes the distribution and motion trajectory of two-dimensional instantaneous velocity of suspended particles in oil, providing theoretical support for the characterization of the instantaneous velocity of suspended particles in the experimental measurement of LDV.