In this paper the basic principle of Digital Particle Image Velocimetry （DPIV） is presented.After the analysis of the conventional algorithm a new motion vector estimation algorithm is proposed for DPIV.The main idea is that the original images are preprocessed firstly to decorrelate

then the sequential similarity detection algorithm （SSDA） is connected with the phase estimation algorithm （PEA） to get much shorter processing time and higher precision conveniently.It makes the near real time processing possible.Although this method is proposed for DPIV

the basic idea can be used in general motion vector estimation.