The invention relates to a simulation method and system for a flexible direct current power transmission device. The method comprises the following steps that: obtaining the reactance and the voltageof a bridge arm, the capacitance of a submodule and a submodule number in the bridge arm; on the basis of the reactance of the bridge arm, the capacitance of the submodule, the submodule number in thebridge arm and a pre-established modularized multi-level current converter model, simulating the flexible direct current power transmission device, and obtaining flexible current and electromechanical transient state operation characteristics under different working conditions of a direct current power grid; and constructing the pre-established modularized multi-level current converter model through a main circuit parameter, an alternating current side equivalent voltage source control quantity and a direct current side controllable current source control quantity.