Traditional distribution state estimation only contains topological constraints and linear impedance branch constraints. With distributed generators (DGs) penetrating into distribution network, lots of negative and zero sequence control equations exist. For unbalance state estimation, there are zero and negative sequence constraints except linear branch constraints. The three-phase distributed generators’ models in state estimation are firstly proposed. And then a state estimation method based on modified nodal analysis is proposed and numerical tests’ results show the difference between considering and not considering distributed generators’ models.