The invention respectively adopts a direct energy balancing mechanism to realize the dynamic decoupling between a steam turbine power regulating loop and a boiler burning regulating loop and a direct mass (flow) balancing mechanism to realize the dynamic decoupling between a steam turbine power regulating loop and a boiler water supply regulating loop, and decouples a usual direct current boiler unit 3*n multi-variable parallel control system onto a decoupling control loop in a hierarchical control structure. The boiler burning regulating loop cancels an usual front side pressure series regulator, and takes the enthalpy increased deviation of an evaporation heated surface of a boiler as the control input; and the boiler water supply regulating loop is designed into fuel-water ratio regulation with a steam turbine power instruction as the input; and the dynamic compensation between boiler burning and water supply is designed. The method best eliminates the coupling impact among all theregulating loops, so that the adjustment is convenient, and the control quality of the direct current furnace unit coordinating control system under the working conditions of variable pressure and variable load is improved.