A numerical model of mussel farm in current was developed to analyse its hydrodynamic performance, in which the mussel dropper was simulated as a porous media. The Reynolds-Average Naiver–Stokes (RANS) equation was applied to simulate the flow around the mussel farm, and the Darcy–Forchheimer equation was adopted to consider the effect of the porous media. A slew of physical model tests were used to validate the numerical model. The results indicate that our numerical model is appropriate to investigate the hydrodynamic behaviour of the mussel droppers in current. The hydrodynamic performance of mussel farms in different water depths was numerically investigated. In addition, the influence of the mussel dropper density and the oblique current was analysed comprehensively. The results indicate that the shielding effect of mussel droppers is increased with the increasing water depth.