The invention provides a modularized multi-level converter with the bridge arm redundancy function and a control method of the modularized multi-level converter. The modularized multi-level converter comprises six current conversion bridge arms, wherein the current conversion bridge arms are connected in series in the mode that every two adjacent current conversion bridge arms serve as a set, the serial connection point between every two adjacent current conversion bridge arms is connected to an alternating-current system, the two ends of each set of current conversion bridge arms are connected with the ends of the adjacent set of current conversion bridge arms in a star-shaped mode, and each current conversion bridge arm is formed by connecting a plurality of power modules, an electric reactor and a switching circuit in series. The control method of the modularized multi-level converter comprises the steps that when the modularized multi-level converter is in a static var compensator state, and normally runs, the switching circuits are kept in a current path closing state, and when a certain bridge arm of the modularized multi-level converter cannot continue working due to failures, the bridge arm is closed, and the switching circuits, connected to the same point in a start-shaped mode, of the two corresponding bridge arms are opened. According to the modularized multi-level converter with the bridge arm redundancy function and the control method of the modularized multi-level converter, the modularized multi-level converter in the static var compensator state can continue working under the condition that a certain bridge arm cannot run, and reliability of the modularized multi-level converter is improved.