The invention provides a fault reconstruction optimization control method for a cascaded H-bridge medium-voltage wind-power converter. The method is applied to a cascaded H-bridge converter connected with a medium-voltage permanent-magnet direct-driven synchronous generator; and each phase of the cascaded H-bridge medium-voltage wind-power converter includes N power units, wherein the N is a positive integer larger than 1. The method comprises: a converter fault monitoring system obtains each phase of fault power unit information of a converter; a neutral point offset voltage and a maximum output voltage of the cascaded H-bridge medium-voltage wind-power converter in a corresponding fault state are determined; and according to a fault state, a wind speed, and generator output power information, an optimal pitch angle is determined, so that maximization of the output power of the medium-voltage permanent-magnet direct-driven synchronous generator in the corresponding fault state is realized. Therefore, when the cascaded H-bridge medium-voltage wind-power converter is in a fault state, the output voltage of the converter is balanced and the output power of the wind turbine generator is optimized.