Under the working condition combinations different kinds of fillers and inlet flow rates of the HABR reactor，the flow states in the first chamber were measured by particle image velocimetry (PIV), the flow data of the critical section in the upflow zone of the HABR reactor were observed, the relationship curves were obtained among fluid-pase velocity, vorticity intensity and flow rate, and the related flow field characteristics including velocity vector diagram，streamline pattern and vorticity distributions were analyzed．The results showed that, for HABR, reasonable choice of filler material types could guarantee good state of inflow, effectively prevent loss of local flow and the sludge, ensure highly efficient and stable operation of HABR. Under this experimental condition, it is concluded that the overall flow pattern of the reactor was the best when the reactor was filled with suspended ball filler．