Abstarct: One of the most important issues in the hovering control unit for STOVL is to achieve the best performance in the presence of uncertainties. Most of the works reported in the literature is baxsed on linear control. In this thesis, a nonlinear optimal control method is adopted to solve the hovering STOVL airplane robust problem. First, the dynamic equations of the STOVL aircraft are expressed in the form of state-space representation. Then, the robust controller is designed considering the coupling between the rotating moment and the transverse force of the aircraft. Finally, to show the feasibility of the proposed control method, numerical simulations are reported with/without PSO algorithm.