The invention discloses a simulation acceleration model for modular DC/DC converter. N sub modules (LLC (logical link control) resonant converters) are serially and parallelly connected to form the modular DC/DC converter. The simulation acceleration model comprises a computer program module and N sub module external circuits, internal circuits of the sub modules are equivalent to four groups of discretized mathematic models, and the discretized mathematic models are written into the computer program module by the aid of Fortran languages. The simulation acceleration model is applicable to theoccasion such as electro-magnetic transient simulation of modular DC/DC converters containing a lot of sub modules. Compared with an initial simulation model, running time can be greatly shortened, and the simulation acceleration model has high simulation accuracy.