The present invention discloses a fixed-structure vertical takeoff and landing aircraft based on the two flight control systems. The aircraft comprises an aircraft structure and the flight control systems. The aircraft structure comprises a fuselage, fixed wings, a steering engine system and a plurality of engines installed on the peripheral side of the fuselage or the ends of the fixed wings. The flight control systems include the multi-rotor flight control system and the fixed-wing flight control system which are relatively independent or integrated in the same flight control system. Free switching between a multi-rotor vertical takeoff and landing mode and a fixed-rotor high-speed cruising mode is achieved by controlling opening and closing of output channels of the multi-rotor flight control system and the fixed-wing flight control system relative to the steering engine system and the engines through a computer.