Abstract: The principal formula of digital holography was deduced and verified from the analysis of holography using Hugeness-Fressnel theory and computer simulation. The thin focus depth of reconstructed 3-D digital image using in holography particle image velocimetry was created by a digital image phase filter method. The velocity vector field with 3-components in 3-D space was computed by 3-D cross-correlation algorithm with thin depth image slices after using phase filter and non-linear image filter. The 3-D vector and streamline results in a cubic flow field were achieved by using DHPIV technique. The results demonstrated an important step was made for the practicality of holography PIV.