In order to solve the problem of excessive calculation of mesh deformation and mesh tension in numerical simulation, an improved mesh group method based on centralized mass method is proposed in this paper. The improved method keeps the volume and mass of the mesh before and after the mesh group, and the deformation of the mesh after the improved method is similar to that before the mesh group by adjusting the hydrodynamic coefficient and axial stiffness. Based on the potential flow theory, the numerical model of "Shenlan No.1" was established to analyze the strain and deformation of the mesh under different flow velocity, wave steepness and compactness. The results show that the mesh tension and deformation increase with the increase of flow rate and compactness, but the tension uniformity decreases with the increase of flow rate and compactness. The maximum tensile value of the mesh appears in the middle area of the top tie point, and the maximum deformation value appears in the middle and upper area of the mesh. The top tie point breakage and bottom tie point breakage have the greatest influence on the mesh. The improved mesh clustering method is accurate and effective, and has good reference value for improving the simulation efficiency and calculation accuracy of the cage hydrodynamics. The results can provide some theoretical support for far-reaching Marine aquaculture.