In order to improve the mooring efficiency and economic benefits of Floating Offshore Wind Turbine (FOWT), the OC3 Hywind mooring system of NREL 5 MW offshore floating generator set is taken as the research objective. A novel design method of multiline shared anchor is studied, that is, the adjacent wind turbines in the wind farms share anchors instead of being moored separately. The multiline anchor net force is computed as the vector sum of the contributing mooring line tensions acting on the anchor. The time domain simulation is performed in SIMA RIFLEX, the dynamic response of the multiline shared anchor mooring system is analyzed and the cost is evaluated. the results show that: for large scale offshore wind farms, using 3-line and 4-line shared anchor design can reduce the number of anchors required by 66.7% and 75.0%, respectively; in terms of dynamic response, compared with the conventional single-line mooring, the 3-line and 4-line anchor load of shared anchor design is reduced; for large-scale wind farm with 100 wind turbines, the mooring anchor cost could be reduced by 55.94% and 63.49% by adopting the design of 3-line and 4-line shared anchor. The study can provide reference for the application of shared anchor mooring in the offshore wind farm.