In recent years, the cross-regional interconnection of power grid is gradually strengthened, and this large-scale network interconnection ensures electricity But it increases the complexity of the dynamic process of the power grid, and small local faults may occur in chain The response was extended to the entire power grid. Traditional linkage fault analysis methods usually use differential equations, and their solving process is very simple In some defects, complex network theory opens up new ideas and methods for the study of grid chain faults. This paper introduces the basic concepts, parameters and models of complex networks, and analyzes the characteristics and modes of each parameter The characteristics of each type. The degree is taken as the index to identify the vulnerability of the line, and two methods are used: random attack and deliberate destruction In this paper, a new load loss ratio index is established to evaluate the impact of faults on the power grid and analyze the linkage Temporal and spatial characteristics of fault propagation. A 1029 node system of Zhejiang Provincial Power grid and a 197 node system of Northwest Power Grid were built by matpower The validity of the study is guaranteed. Through the analysis, the random attack pattern is obtained for the power grid when the attack proportion is low The extent of the impact is small, while the mode of deliberately destroying several nodes and lines is adopted, although the proportion of attacks is relatively high Low, the power grid could still suffer significant impacts. This shows that the high-degree nodes and the high-degree lines are on the grid The safe and stable operation plays an important role.