Structural hole is an important concept to estimate patterninduced competitive power for each node in a social network.Principal component analysis(PCA)was proposed to evaluate the structural holes in a global way.Ginicoefficient for social network was defined to measure quantitatively the structural holes.As examples,the Gini coefficients for some realworld networks and the extended BarabsiAlbert scalefree networks were calculated.It is concluded that the bigger the contribution of S in the network,the more uniform the importance of modes and the greater the degree of structural holes; Conversely,the smaller the contribution of S,showing the network structure information mainly concentrated in part of nodes,the smaller the degree of structural hole.