With the widespread application of distributed generation (DG), their utilization rate is increasingly higher and higher in the power system. This paper analyzes the static and transient impact of large-scale DGs integrated with the distribution network load models on the power grid. Studies of static voltage stability based on continuous power flow method have shown that a reasonable choice of DG's power grid position will help to improve the stability of the system. The transient simulation results show that these induction motors in the distribution network would make effect on the start-up and fault conditions, which may cause the instability of DGs and grid. The simulation results show that modeling of distributed generations and loads can help in-depth study of the microgrid stability and protection design.