An engineering analytical model applied in dynamic simulation of the grid-connected photovoltaic system is established based on the DIgSILENT software, including PV array, inverter and the control system. The system adopts the double-loop feedback control with the inner-loop of current, the outer DC-voltage loop tracks the maximum power point of PV cells while the AC-voltage loop controls the reactive ouput. At last, the output characteristics of PV power generation system are analyzed under the variation of actual solar radiation, the dispatch of the active power and grid voltage dips. The results of the simulation show that the proposed method is practical and valid, the model output is similar to the actual one basically. This system can track the maximum power point automatically with high accuracy and response to the grid dispatching center rapidly, and provide reactive power during the voltage dip. It can be applied in paralleling operation analysis of photovoltaic system and makes a good groundwork for the practical engineering research.