The invention discloses a large-torque magnetic suspension flywheel, which can be used as an execution mechanism for attitude stabilization and attitude maneuver of spacecrafts such as a satellite, an earth observation platform and the like. The magnetic suspension flywheel mainly consists of a base, a sealing cover, a radial decoupling conical magnetic bearing assembly, a core shaft, a rotor assembly, a Lorentz force magnetic bearing assembly, a motor assembly, a sensor assembly and the like. The core shaft is positioned in the center of the wheel body, a stator assembly is positioned at theradial outer side of the core shaft, the rotor assembly is arranged at the radial outer side of the stator assembly, the rotor assembly consists of a wheel flange and a wheel hub, and the Lorentz force magnetic bearing assembly consists of a magnetic bearing stator part and a magnetic bearing rotor part; an adapter plate is connected with the core shaft, the stator assembly and a motor stator; and the sensor assembly consists of a sensor shell and a sensor. The components of the flywheel are arranged reasonably and compactly, the flywheel can be used for attitude stabilization of the spacecraft, and attitude maneuver of the spacecraft can be realized by using large control torque provided by gyroscopic effect of the magnetic suspension flywheel.