The present invention relates to a multidimensional modeling method and a simulation method for a modular multilevel converter, comprising steps of: (1) establishing equivalent models of half-bridge submodules and establishing Thevenin equivalent models of submodules according to the Thevenin's Equivalence Theorem; cascading the Thevenin equivalent models of submodules to establish a high-speed equivalent model of a modular multilevel converter; (2) acquiring stray parameters, putting a stray capacitor and a stray resistor at corresponding positions in the high-speed equivalent model established in step (1), to establish a wide frequency model of the modular multilevel converter; and (3) replacing a submodule of each bridge arm of the wide frequency model established in step (2) with a detailed electromagnetic transient model, to establish a multidimensional model of the modular multilevel converter. The present invention can not only greatly improve the efficiency of system simulation and realize device-level electromagnetic transient analysis, but also simulate the effects of stray elements on system operation so as to facilitate efficient and accurate simulation analysis of the modular multilevel converter.