Abstract: The adjustment of the power grid by breaking parts of specified voltage grade transmission lines can increase the electrical distance among over-standard nodes and source nodes in the network.This is a simple and effective measure of limiting short circuit current and widely applied in the power system operation.According to the application characteristics of breaking transmission lines in the adjustment of power grid structure,and considering the current limit requirements as well as maintaining the power grid security,an index fitness function based on impedance sensitivity weighted value is proposed to reflect the degree and proportionality of current limiting effect.The power grid adjusting model with breaking the transmission lines is proposed.The ant colony optimization is improved in the aspects of path selection strategy,pheromone updating and adjustment factor to obtain a rapid calculation and global optimization of power grid adjustment.The feasibility and effectiveness of the proposed algorithm is verified by the network adjustment scheme test of Guangdong power grid.