The invention discloses a grid-connected photovoltaic power generation system electromechanical transient model based on power decoupling control. The grid-connected photovoltaic power generation system electromechanical transient model based on power decoupling control is characterized by comprising a photovoltaic battery unit, a maximum power tracking unit, a direct current voltage stabilizing unit, a PQ decoupling control unit and a protective configuration unit, wherein the output end of the photovoltaic battery unit is connected with the input end of the direct current voltage stabilizing unit, the output end of the direct current voltage stabilizing unit is connected with the input end of the photovoltaic battery unit and the input end of the PQ decoupling control unit, the output end of the PQ decoupling control unit is connected with the input end and the output link of the direct current voltage stabilizing unit, the output end of the maximum power tracking unit is connected with the input end of the photovoltaic battery unit, the input end of the direct current voltage stabilizing unit and the input end of the PQ decoupling control unit, and the protective configuration unit is connected with the output link. The grid-connected photovoltaic power generation system electromechanical transient model based on power decoupling control is suitable for transient stability calculation in the electromechanical transient simulation process of the power system, can analyze the transient stability of a photovoltaic access system, and can study the reactive voltage problem of part of the power grid.