The VSC based Multi-terminal DC (MTDC) grid is a promising approach for the integration of renewable energy sources. It’s necessary to study the power flow of the AC/DC network. A unified power flow algorithm for AC/DC network using Modified Augmented Nodal Analysis (MANA) is proposed. The detailed steady state model and different control modes of VSC station, MANA based AC and DC network model is established firstly. Then a unified power flow algorithm is developed based on the Newton MANA method, the node injection currents and branch currents of AC/DC network are added as unknown variables and solved simultaneously with the unknown node voltages. The effectiveness of the proposed algorithm is verified by numerical tests on modified IEEE 30-bus system. This work is supported National Natural Science Foundation of China (No. 51477083).