To investigate the influence of the inter-turbine spacing on the performance of the floating offshore wind turbine (FOWT) in the floating wind farm, coupled aero-hydrodynamic simulations of two spar-type FOWT models with inter-turbine spacing variation under shear wind and regular wave conditions are performed in the present work. An unsteady actuator line model (UALM) is embedded into in-house code naoe-FOAM-SJTU to establish a fully coupled CFD analysis tool for numerical simulations of FOWTs. From the simulation results, the unsteady aerodynamic power and thrust are obtained, and the hydrodynamic responses including the six-degree-of-freedom motions and mooring tensions are available. Detailed flow visualizations of wake velocity profiles and vortex structures are also illustrated. The coupled performance of floating offshore wind turbines with inter-turbine spacing variation are analyzed, and the influences of inter-turbine spacing on aero-hydrodynamic characteristics of coupled wind-wave flow field are discussed. It is found that the power output of downstream wind turbine increases with inter-turbine spacing. Coupled aero-hydrodynamic characteristics of flow filed are significantly affected by inter-turbine spacing.