Abstract: The network attacks against the power system of hostile countries can cause great damage with less attack resources. From the perspective of attackers, this paper proposes a network attack strategy for weak state of power system. Firstly, tthe correlation matrix based on the grid topology data is established, and the load shedding caused by the attack under different information acquisition amounts is calculated through the linear programming model. Then an automatic attack strategy is proposed to maximize the attack effect. The effectiveness of the proposed strategy is verified by simulation analysis in different scenarios.