Under the complex hydrodynamic environment in the open sea area of the Bengal bay,the plane layout of FSRU and LNG ships parallel operation was adopted.The movement,mooring force and impact force of the ship under the combined action of wind,wave and current were calculated.The allowable working wave height under different wave action angles and different periods was calculated.The berthing stability conditions of alongside-banking model and double-side banking model in this sea area were given.The results show that：1） The six degrees of freedom motion,mooring force and impact force of FSRU and LNG ship increase with the increase of wave height and wave period.2)Under the influence of long-period wave,the allowable berthing wave height of FSRU and LNG ship is significantly reduced,and the surge motion is easier to exceed the standard.The unloading of LNG ship is beneficial to the berthing stability.The double-side banking of FUSR and LNG ship can more effectively resist the wave impact.