The influence of floating structure on the downstream flowing structure in the flowing water was studied by using a physical model test. By comparing the flowing structures under different aspect ratios and water levels, the flowing velocity distribution, non-uniform coefficient and the length of recirculation zone of the characteristic cross section were analyzed. The results show that the influence of aspect ratios on the velocity distribution and the non-uniform coefficient is not obvious, while the water-level difference has a great influence and it shows an increasing trend with the increase of water level. At the same time, the length of recirculation zone is more sensitive to the aspect ratio and water level. In the practical engineering, attentions should be paid to the engineering problems caused by the change of water level. This study can provide references for the design of floating structure as well as the change rule of downstream flowing structure in current during the process of running.