The invention relates to a concurrent boiler steam-water separator modeling method and system. The method comprises the steps of based on a MUSE simulation environment, performing simulation model building on a steam-water separator to obtain a corresponding steam-water separator simulation model; based on the law of conservation of mass and the law of conservation of energy and the physical properties of working mediums, performing mathematical modeling on the steam-water separator simulation model to obtain a mechanism model of the steam-water separator; when the steam-water separator simulation model is in an operation simulation process, analyzing the simulation working conditions the steam-water separator simulation model is located currently in real time; in a current parameter calculation period, performing parameter calculation on the simulation working conditions the steam-water separator simulation model is located currently by using the mechanism model to obtain working medium parameters in the current parameter calculation period, wherein the simulation working conditions include a water supply start state, a wet-state operation state, a dry-state operation state, a dry state and wet state conversion state and a supercritical state. The method and the system realize simulation modeling on a steam-water separator in a concurrent boiler.