Based on the complex network theory, three kinds of vulnerability indices are proposed to assess the vulnerability of the power grid with distributed generation(DG). The structure based index can consider the influence of network topology and node power on the supply efficiency. And the attack vulnerability index can assess the ability of the system to withstand node or line removal. Further, the index based on operational condition can reflect the power balance level of the whole power grid. At last, simulation results verify the validity of the proposed indices and the role of DG in improving transmission property and anti-disturbance ability of the power network.