The invention provides a modeling method for a dynamic model of a modular multi-level convector. The method comprises the following steps of establishing an upper bridge single submodule switch period average model and an upper bridge arm single submodule small signal communication model; establishing an upper bridge arm switch period average model and an upper bridge arm small signal communication model; establishing a lower bridge arm switch period average model and a lower bridge arm small signal communication model; establishing a lower bridge single submodule switch period average model and a lower bridge arm single submodule small signal communication model; and establishing a modular multi-level convector switch period average module and a modular multi-level convector small signal module. The established dynamic model of the modular multi-level convector facilitates analysis on a dynamic property and a frequency response characteristic of the modular multi-level converter, facilitates cascade control strategy design of the device, and achieves description of internal state quantity.