Résumé : Compared with the conventional floating offshore platforms, the FOWTs (floating offshore wind turbines) are subjected to larger wind heeling moments to cause significant pitch motions which bring challenges to the power generation efficiency and structure safety, due to the existence of wind turbines. In addition, the dynamic cable connected with FOWT is subject to a load that is greatly affected by horizontal motions of FOWT. Therefore, the inhibitions of horizontal and pitch motions are vital to FOWT. However, conventional mooring systems mainly inhibit the horizontal motions of floating structures. In this paper, an innovative type of mooring system is proposed to inhibit both the horizontal and pitch motions of FOWT. The analytical results based on the innovative mooring system are compared with those of conventional mooring system. In addition, the mechanism of restoring forces and moments of mooring systems are analyzed and discussed.