Taken the mooring system of a 10 MW floating wind turbines as the research object, the mooring line tension and floater motion under different working conditions and mooring parameters are investigated. The causes of the slack-taut phenomenon of the mooring line as well as the influence of mooring parameters on the mooring property are studied. The results show that increasing the height of the fairlead and adding clumps or buoys on mooring lines can effectively eliminate the slack state of the mooring, reduce the ultimate tension of the mooring line and ensure the safety of the mooring system.