Considering that flexible net is easy to deform under the action of current, which will reduce the effective volume of the cage and accompany the tearing risk of the net, it is important to study the change of the flow field around the net and the deformation characteristics of the net. Based on the shear stress SST K-ω turbulence model and combined with the one-way Fluid-Structure Coupling (FSI) method of ANSYS Workbench, the pressure of the net is applied as an input load on the surface of the planar net, the flow field characteristics of the planar nylon knotless net under different flow rates, net solidities and angles of attack are studied, and the finite element model of the large-deformation nonlinear net structure is analyzed. The results show that the one-way coupling numerical simulation based on FSI is feasible for the analysis of the planar net deformation and flow field characteristics, and the decrease of flow velocity caused by net is different under different angles of attack. The hydrodynamic coefficient of the net is obtained under different flow rates, net solidities and angles of attack. The characteristics of equivalent stress distribution and deformation varied with the angles of attack are also represented. It is found that the stress from the center net cable to the edge net cable gradually decreases, and the maximum stress is found near the fixed end of the net cable.