The influence of floating structure on the downstream flow structure in the finite flowing was studied by using a physical model test. By comparing the floating structure in different positions and under discharge conditions, the distribution of flow velocity, the non-uniform coefficient and the length of recirculation zone of the characteristic cross section are analyzed. The results show that the influence of floating structure position on the velocity distribution and the non-uniform coefficient is clearly observed, and the discharge condition also has a great influence on them. Besides, this effect shows an increasing trend with the increase of flow discharge. Both different positions and discharges have a significant impact on the length of the recirculation zone. In the practical engineering, attention should be paid to the engineering problems caused by the change of the positions and discharge. The change rule of downstream flow structure of floating structures during the process of running is obtained in this study, which can provide references for the design of floating structural stability.