Abstract: The particle tracking velocimetry (PTV) algorithm based on Delaunay Tessellation (DT), named as 3DT PTV is improved to match particles from two consecutive instants in the three-dimensional field. In 3DT PTV, the particle pairing is summarized out of the pattern pairing, in which a pattern DT grid is adopted in the selection of pattern candidate to enable 3DT PTV free of parameters and applicable in unevenly distributed flow, and a pattern identifying vector is proposed for the pattern similarity judgment. The result of particle pairing is then doubled and refreshed by the processors of “Dual Computation” and “Selection by Probability”. 3DT PTV is tested by standard synthetic flows with self-defined perturbations. The merit of 3DT PTV confirmed by the test result is the high accuracy in addressing complex flow with noticeable ratio of particles having no pair.