The invention discloses a cascaded communication architecture applicable to a modular multilevel converter control system. According to the cascaded communication architecture, the maximum quantity of sub-modules controlled by one converter control device is Q, and Q is larger than N; N cascaded sub-modules of one bridge arm of a multilevel converter valve are M sub-sections in sequence; the quantity of the converter control devices is M; each converter control device is used for being connected with and controlling the sub-module in one corresponding sub-section; the M converter control devices are further used for cascade of the M sub-sections of the same bridge arm; such a cascade manner that every two adjacent converter control devices are cascaded through optical fiber communication or electric communication. The cascaded communication architecture has the advantages that a single bridge arm is cooperatively controlled by one or more converter control devices; through cascade of the converter control devices, information such as the quantity of faulty modules and the emergency fault state are shared among a plurality of the converter control devices, so as to achieve cooperative control of a plurality of the sub-modules of the single bridge arm, facilitate expansion of the system, and reduce the complexity of software and hardware design for the system.