It is very difficult to measure the full flow field because of narrow gallery and complex hydraulic flow pattern on the corner in the reciprocating baffled flocculation tank. The particle image velocimetry and middle field tests and numerical simulation are used. This paper uses an advanced particle image velocimetry technology, and develops a two-dimensional numerical model. It can be seen clearly that the improvement of hydraulic conditions of flow field in the different boundary conditions through the flow particle image. By means of the middle field tests, coagulation effect has improved significantly in the improved flocculation, and the addition of tiny eddies can achieve effective flocculation. The comparison shows that the numerical results are in agreement with the experiment results of the flocculation tank.