In　this　article,　a　mathematical　model　of　hydrodynamic　force　was　established　to　model　the　influence　of　wall　in　realizing　the　precise　control　and　maneuverability　of　a　complex-shaped　underwater　robot.　A　hydrodynamic　model　of　a　robot　for　use　in　a　nuclear　reaction　pool　was　presented　containing　not　only　hydrodynamics　coefficients　but　also　a　wall　hydrodynamic　force　term,　which　was　often　ignored　for　robots　used　at　sea.　First,　hydrodynamic　coefficients　in　the　model,　including　viscous　and　inertial　coefficients,　were　solved　by　simulating　steady-state　and　unsteady-state　motion　by　computational　fluid　dynamics.　Next,　the　wall　hydrodynamic　force　was　calculated　by　computational　fluid　dynamics　for　different　velocities　and　distances　from　the　wall,　and　the　scope　of　influence　of　the　wall　was　identified.　Finally,　hydrodynamic　coefficients　without　the　wall　effect　and　with　the　wall　hydrodynamic　force　under　different　conditions　were　measured　experimentally　in　a　circulating　water　tank.　The　result　demonstrated　the　accuracy　of　hydrodynamic　calculation　by　computational　fluid　dynamics　and　verified　the　reliability　of　the　hydrodynamic　mathematical　model.