Abstract: The three-dimensional particle dynamic analyzer is a kind of laser velocity-measuring instruments with laser doppler frequency and phase deviation,which is widely used in measuring of the velocity and diameter of particles in two-phase folw.During the processes of data acquisition,the original data doctiments,which are produced automatically and stored in binary system,are not only unconvenient for reading butalso unable to transfer directly for next step calculation.In this paper,a new data processing methed used C language program has been put forword to obtain the characteristics of particles,which is convenient for further utilization and development of original data software pf 3D-PDA.