In view of distributed generation grid-connected problems, analyzed the impact of distributed generation on active power loss and voltage. Described DG type and power flow calculation model and introduced the methods about various flow calculation models. Calculated power flow in IEEE 30 node system by PSASP software and analyzed the impact of DG position and capacity on active power loss and voltage. The simulated results showed that when the distributed generation in the same position interconnected, the larger capacity of distributed generation has a relative larger influence on active power loss and the node voltage; when the distributed generation in the same capacity interconnected, the grid-connected position is closer to the end of the system, the system voltage promoting is more obvious and the enhancing for voltage is highest in the gird-connected position and its vicinity.